Based on 6 morphological characters of Cristaria plicata, Hyriopsis cunimgii , Anodonta woodiana pacif ica, A . woodiana elloptica and A . globosula in Unionidae, multivariate morphometrics were used to investigate their morphological variations among 5 species and 6 region populations. In the result of principal component analysis, two principal components ( PC) were constructed by factor loadings, in which the first principal component ( PC1) was affected by 4 characters and the PC2 was affected by 1 character, and the contributory ratio of two PC was 54. 17% and 34. 08% respectively. The results of principal component analysis and cluster analysis revealed that the morpho logical character of C . plicata and H . cunimgii was similar and the morphological character was similar between A . woodiana elloptica and A. globosula. ANOVA and t-test indicated that different region populations of C. plicata and H . cunimgii showed some morphological variations respectively. The discriminant functions of f ive unionid species were established, and the discriminant accuracy was 100% for H . cunimgii and A . woodiana pacif ica, 98. 92%, 86. 36% , 96. 88% for C. plicata, A. woodiana elloptica and A. globosula in turn, so the average discriminant accuracy was 97. 83%.