diff --git a/main.py b/main.py
index 98f12c2..dd46e96 100644
--- a/main.py
+++ b/main.py
@@ -35,6 +35,13 @@ STATE_FILE = "bot_state.json"
 STOP_ORDERS_FILE = "stop_orders.json"
 
 
+def _calc_atr_stop_price(entry_price: float, atr: float) -> float:
+    """根據 ATR 動態計算止損價，帶上下限。"""
+    atr_pct = (atr * config.ATR_SL_MULTIPLIER) / entry_price
+    bounded_pct = max(config.ATR_SL_MIN_PCT, min(config.ATR_SL_MAX_PCT, atr_pct))
+    return round(entry_price * (1 - bounded_pct), 8)
+
+
 def _load_state() -> dict:
     if os.path.exists(STATE_FILE):
         try:
@@ -131,7 +138,10 @@ def run_cycle():
         if min_amt > 0 and amount < min_amt:
             continue
 
-        expected_stop = round(entry * (1 - config.STOP_LOSS_PCT), 8)
+        # Use stored stop price if available (preserves ATR-calculated value);
+        # fall back to fixed % for legacy positions without a stored price
+        tracked = tracked_stops.get(sym, {})
+        expected_stop = tracked.get("stop_price") or round(entry * (1 - config.STOP_LOSS_PCT), 8)
         existing_stops = stop_orders_by_sym.get(sym, [])
 
         if existing_stops:
@@ -155,7 +165,7 @@ def run_cycle():
             time.sleep(0.3)  # Wait for Bitfinex to release locked balance
 
         logger.warning("Position %s missing/outdated stop-loss, placing now", sym)
-        sl = trader.place_stop_loss_order(sym, amount, entry)
+        sl = trader.place_stop_loss_order(sym, amount, entry, stop_price=expected_stop)
         if sl:
             # Update stop_orders_by_sym so step 10 sees the correct stop ID
             stop_orders_by_sym[sym] = [{"id": sl["order_id"], "symbol": sym,
@@ -336,7 +346,7 @@ def run_cycle():
             continue
 
         ind_df = indicators_by_symbol.get(signal.get("symbol"))
-        validated, reject_reason = risk_manager.validate_trade(signal, port, ind_df)
+        validated, reject_reason = risk_manager.validate_trade(signal, port, ind_df, current_prices)
         if validated is None:
             logger.info("Signal rejected by risk manager: %s %s — %s", action, signal.get("symbol"), reject_reason)
             rejected.append({**signal, "reject_reason": reject_reason})
@@ -400,7 +410,21 @@ def run_cycle():
                 # Place new stop-loss for TOTAL position amount at new avg entry
                 total_amount = pos.get("amount", amount)
                 entry_price = pos.get("entry_price", price)
-                sl = trader.place_stop_loss_order(sym, total_amount, entry_price)
+
+                # ATR-based dynamic stop price
+                atr_stop = None
+                ind_df = indicators_by_symbol.get(sym)
+                if ind_df is not None and "atr" in ind_df.columns:
+                    atr_val = ind_df["atr"].dropna().iloc[-1] if not ind_df["atr"].dropna().empty else None
+                    if atr_val and atr_val > 0:
+                        atr_stop = _calc_atr_stop_price(entry_price, atr_val)
+                        atr_pct = (1 - atr_stop / entry_price) * 100
+                        logger.info("ATR stop for %s: ATR=%.6g, stop=%.6g (%.1f%%)",
+                                    sym, atr_val, atr_stop, atr_pct)
+                if atr_stop is None:
+                    logger.info("ATR unavailable for %s, using fixed %.0f%% stop", sym, config.STOP_LOSS_PCT * 100)
+
+                sl = trader.place_stop_loss_order(sym, total_amount, entry_price, stop_price=atr_stop)
                 if sl:
                     stop_price = sl["stop_price"]
                     # Update stop_orders_by_sym so subsequent actions in this cycle see it
diff --git a/trader.py b/trader.py
index a86d1a3..f021444 100644
--- a/trader.py
+++ b/trader.py
@@ -65,13 +65,15 @@ def execute_trade(signal: dict, current_prices: dict, mode: str | None = None) -
     return trade_result
 
 
-def place_stop_loss_order(symbol: str, amount: float, entry_price: float, mode: str | None = None) -> dict | None:
+def place_stop_loss_order(symbol: str, amount: float, entry_price: float,
+                          stop_price: float | None = None, mode: str | None = None) -> dict | None:
     """Place an EXCHANGE STOP order as stop-loss after a BUY.
 
     Args:
         symbol: Trading pair (e.g. tBTCUST)
         amount: Position size in base currency (positive, will be negated for sell)
         entry_price: The buy entry price
+        stop_price: Explicit stop price (e.g. from ATR calc). Falls back to fixed % if None.
         mode: "paper" or "live"
 
     Returns:
@@ -85,16 +87,18 @@ def place_stop_loss_order(symbol: str, amount: float, entry_price: float, mode:
         logger.info("Skip stop-loss for %s: amount %.6f < min %s", symbol, abs(amount), min_amt)
         return None
 
-    stop_price = round(entry_price * (1 - config.STOP_LOSS_PCT), 8)
+    if stop_price is None:
+        stop_price = round(entry_price * (1 - config.STOP_LOSS_PCT), 8)
     # Truncate to 8 decimals (Bitfinex wallet precision) to avoid "not enough balance"
     amount = math.floor(abs(amount) * 1e8) / 1e8
     sell_amount = -amount  # negative = sell
 
     if mode == "paper":
         order_id = f"paper_sl_{int(time.time() * 1000)}"
+        sl_pct = (1 - stop_price / entry_price) * 100 if entry_price else 0
         logger.info(
             "PAPER STOP-LOSS placed: %s sell %.6f @ %.6g (entry %.6g, SL %.1f%%)",
-            symbol, abs(amount), stop_price, entry_price, config.STOP_LOSS_PCT * 100,
+            symbol, abs(amount), stop_price, entry_price, sl_pct,
         )
         return {"order_id": order_id, "stop_price": stop_price, "symbol": symbol, "mode": "paper"}