The acid phosphatase(ACP) from grass carp,channel catfish and mud eel muscles were extracted and partial properties of the crude enzyme were investigated.The results showed that the optimal pH values of ACP of grass carp,channel catfish and mud eel muscle were 5.0,5.8 and 5.6,respectively.The optimal temperatures were 60 ℃,37 ℃ and 43 ℃,respectively.ACP of grass carp and mud eel muscle were stable in the pH range of 5-9,while ACP of channel catfish was in the pH range of 5-8.Na+,K+,Mg2+ have no effect on the enzymes,whereas ACP activity was stimulated by Zn2+ and inhibited by Cu2+,Ca2+,Hg2+.ACP activity was also inhibited by cystine,sodium phosphate,sodium pyrophosphate.