This study is based on the material of Japanese scallop (Patinopecten yessoensis Jay) phenotypic characters, and the objective is to analyse correlation relationship, define degree of correlation among characters, establish the regression equation, and to lay a foundation of selective breeding. Data for this study were collected from 126 Japanese scallops at three years old in Zhangzidao Island of Dalian City. The shell length (X₁), shell height (X₂), shell width (X₃), live body weight (Y), soft tissue weight (Z) and adductor weight (W) of 63 male scallops and 63 female scallops were measured individually. The correlation coefficient matrix was calculated respectively. Three body shape traits were used as independent variables, the softtissue weight and adductor weight were used as dependent variable for path analysis, and path coefficients (P_i), determination coefficients (d_i) and correlation index (R²) were calculated. The results show that correlation coefficients between each body shape trait and the live body weight (Y), softtissue weight (Z) and adductor weight (W) are all significantly different (P<0.01). Shell length (X₁) and shell height (X₂) give predominant direct effect and determinacy on the softtissue weight of female scallops; it is the key effective factor. Shell length (X₁) and shell width (X₃) give predominant direct effect and determinacy on the softtissue weight of male scallops; it is the key effective factor. But the key effective factors of mixed scallops are shell length (X₁), shell height (X₂) and shell width (X₃). The key effective factor on adductor weight (W) is only shell width (X₃), shell length (X₁) and shell height (X₂) give slightly direct effect and significant indirect effect through shell width (X₃), is the secondary factor. It was clear from the result of high correlation index that the path coefficient analysis could reveal the truthful relationship between the independent variables and the dependent variable. Eliminate inconspicuousness factor, the multiple regression equation obtained to estimate two anatomical traits as: 1) For female Z= -128.573+1.355 X₂+1.407 X₃; W= -8.216+ 0.869 X₃; 2) For male Z = -138.493 +1.082 X₁+2.524X₃; W = -11.855+0.955 X₃；3) For mixed Z= -133.939 +0.606 X₁+0.679 X₂+ 1.709 X₃; W= -9.525+ 0.896X₃. Efficient scheme of multiple trait selection will be made if we obtain definite quantitative relationship between each two characters. This study provides theoretical evidence and perfect measure target for breeding of Japanese scallop.