diff --git a/server/gameserver/creature.cc b/server/gameserver/creature.cc
index 17c8cef..11d8461 100644
--- a/server/gameserver/creature.cc
+++ b/server/gameserver/creature.cc
@@ -1242,7 +1242,7 @@ void Creature::UpdatePoisoning()
         } else {
             dmg = room->GetGasData().old_area_meta->i->hurt();
         }
-        dmg *= 1 + GetAbility()->GetAttrRate(kHAT_PoisoningReduction);
+        dmg *= 1 - GetAbility()->GetAttrRate(kHAT_PoisoningReduction);
         dmg = std::max(10.0f, dmg);
         DecHP(dmg, VP_SafeArea, TEXT("battle_server_killer_gas", "毒圈"), VW_SafeArea);
         if (dead) {