Abstract: Data for this study were collected from 73 Saxidomus purpurata in Dalian City. The shell length (x1), the shell width (x2), the shell height (x3) and the live body weight (Y) were measured. The correlation coefficient matrix was calculated. The preceding 3 shell characters were used as independent variables, and live body weight was used as a dependent variable for path analysis, path coefficients, determination coefficients and correlation index were calculated, and major morphometric attributes determined. The results showed that all the correlation coefficient between each independent variable and dependent variable (body weight) were significantly different (P<0.05). The shell height gave a predominant direct effect ( 0.589 ) and determinacy on the body weight, it is the key effective factor, whereas shell length and shell width exhibited a slight direct effect (0.4023, 0.3787) on the body weight via shell height. The value of multiple vorrelation index R2 at 0.828 between morphometric and body weight suggests that the selected attributes are practical.The multiple regression equation relating the body weight was established as y=-265.233+0.743x1+2.459x2+3.688x3.