Charybdis japonicais an important economic crab,very popular in Chinese coastal cities.But in recent years,the germplasm resources have been declining,and the work of resources proliferation already received great concern.With the development of artificial breeding and farming,the study of disease development and prevention and control measures is inevitable.Currently,few studies have related to the immune aspects of C.japonica.In order to explore the immune status,the non-specific immune function was studied in four populations of C.japonica from Dalian,Laizou Bay,Haizhou Bay and Xiangshan.Four types of tissues(muscle,gill,hepatopancreas and serum)and seven immunity related enzymes(ACP,AKP,LSZ,MDA,SOD,CAT and GSH-px)were detected.The results showed that the seven kinds of enzymes all exist in the four detected tissues,and the activities were different in different groups.The serum ACP,AKP and LSZ activities of Dalian was significantly higher than that of Haizhou Bay population(P<0.05),and there was no significant difference among other populations(P>0.05).The MDA content varied from different tissues.Dalian population was significantly higher than Haizhou Bay population in hepatopancreas and serum(P<0.05),but there were no significant differences in other tissues(P>0.05).For the SOD,CAT and GSH px activity of hepatopancreas and gill,Dalian population and Haizhou Bay population have shown significant difference(P<0.05).The results of the immunity enzyme activities are quite correlated with those of nonspecific immunity abilities of preventing disease and disease resistance evaluation.