Abstract: [Objective] This study aimed to determine the main phenotypic traits that effect the body weight, and provide the theoretical basis for the parental selection and morphological assisted breeding of P. clarkii. [Method] A total of 350 female and 302 male P. clarkii were selected, and their weight(Y), full length(X1), carapace length(X2), carapace width(X3), abdomen length(X4), first abdomen length(X5) and first abdomen width(X6) were measured. The correlation analysis was adopted to calculate the correlation coefficients. The path coefficients and the decision coefficients were calculated by path analysis. [Result]The correlation analysis showed that all the correlations were highly significant between the traits of the female and male (P<0.01). In multivariate analysis, the morphological traits which did not reach the extremely significant level were eliminated and the multiple regression equations were presented as Y= －34.689+10.629X2+6.479X3+0.803X1 in female P. clarkii and Y=－33.413+5.727X2+6.770X3+2.043X1+3.045X6 in male P. clarkii. The results of the path analysis indicated that the carapace length had the greatest direct effect on body weight in female P. clarkii, followed by the full length, carapace width and the carapace width which mainly affected body weight indirectly through the carapace length. As for male, the carapace length also had the greatest direct effect on weight, followed by the full length, carapace width, the first abdomen width and the first abdomen which had the largest indirect effect on weight through the carapace length, carapace width and the full length. [Conclusion]The above results could lay a foundation for the parental selection in P. clarkii breeding.