In the paper,isozymes(SOD,EST)from liver of alien species Hyriopsis schlegeli(C),H.cumingii(S) and their reciprocal hybrids F_1 were analyzed by vertical polyacrylamide gel electrophoresis.The results indicated that phenotype polymorphism in the isozymes electrophoresis meanwhile some common characters were observed among H.schlegeli,H.cumingii and their reciprocal hybrids F_1.There are 2-5 SOD loci in parental mussels and their reciprocal hybrids F_1.A strong activity of SOD-1 is visible only in F_1SC,and about SOD-2,a strong activity band in F_1SC,while a weak band in F_1CS but no band in parent is observed,respectively.There is a strong conservative band SOD-3 in all mussels and a strong band SOD-4 except in F_1SC,and a strong band SOD-5 except in Hyriopsis schlegeli are visible.4-6 EST loci are visible in the 2 species mussels and their reciprocal hybrids F_1 and all loci have a varying degree of activity but EST-4 invisible in F_1SC and EST-5 invisible in F_1CS.