This paper aims to investigate the effect of environmental factors such as temperature,pH and salinity on the activity of gill Na⁺-K⁺-ATPase in freshwater crayfish,Procambarus clarkii under special environmental factors acclimation or their acute changes.In this research,phosphorus content—Molybdenum blue spectrophotometric method has been applied to determine the gill Na⁺-K⁺-ATPase activity in P.clarkii.The result indicates that activity of Na⁺-K⁺-ATPase varies in accordance to the fluctuations of environmental factors and acute effect of Na⁺-K⁺-ATPase was shown apparently in emergency conditions,which last for 2-8 h.The change became smooth afterwards and the finally activity was the same as the result in acclimate treatment.