diff --git a/webapp/services/BattleDataService.php b/webapp/services/BattleDataService.php
index 526b5714..76174ddc 100644
--- a/webapp/services/BattleDataService.php
+++ b/webapp/services/BattleDataService.php
@@ -517,9 +517,6 @@ class BattleDataService extends BaseService {
                              $onlineNum,
                              $gunFragmentNum,
                              $todayPvpBattleTimes);
-
-            $heroProbability = max($heroProbability, 0);
-            $gunProbability = max($gunProbability, 0);
             $emptyProbability = max(1 - $heroProbability - $gunProbability, 0);
 
             $dropIdx = $this->randWeight(array($heroProbability, $gunProbability, $emptyProbability));
diff --git a/webapp/services/FormulaService.php b/webapp/services/FormulaService.php
index 8fc161f5..7d01a6cd 100644
--- a/webapp/services/FormulaService.php
+++ b/webapp/services/FormulaService.php
@@ -118,7 +118,7 @@ class FormulaService extends BaseService {
                                    0.05 * $weaponTopX * $meta['weapon_topx']
                                ) *
                                pow(2, ($todayPvpBattleTimes % 10) - 1), 1);
-        return $heroProbability;
+        return max(0, $heroProbability);
     }
 
     public static function calcWeaponFragmentProbabilityPvp($params,
@@ -135,15 +135,15 @@ class FormulaService extends BaseService {
             return 0;
         }
         $weaponProbability = min($FragmentNum / $onlineNum *
-                               5 *
-                               (
-                                   0.5 * $rankedTopX * $meta['ranked_topx'] +
-                                   0.25 * $killsTopX * $meta['kills_topx'] +
-                                   0.15 * $heroTopX * $meta['hero_topx'] +
-                                   0.05 * $weaponTopX * $meta['weapon_topx']
-                               ) *
-                               pow(2, ($todayPvpBattleTimes % 10) - 1), 1);
-        return $weaponProbability;
+                                 5 *
+                                 (
+                                     0.5 * $rankedTopX * $meta['ranked_topx'] +
+                                     0.25 * $killsTopX * $meta['kills_topx'] +
+                                     0.15 * $heroTopX * $meta['hero_topx'] +
+                                     0.05 * $weaponTopX * $meta['weapon_topx']
+                                 ) *
+                                 pow(2, ($todayPvpBattleTimes % 10) - 1), 1);
+        return max(0, $weaponProbability);
     }
 
     public static function getHeroPvpTiliTotalValue($heroDb)