To study the effects of morphological attributes on body weight of grass carp, 287 2 year old individuals were sampled for measuring seven metric traits, including the total length, standard length, head length, body width, body height, interorbital width, length before anus, The relationship between morphological attributes and body weight was quantified by correlation analysis, path analysis and multiple regression analysis to determine the major morphological attributes. The results showed that the correlation coefficients of each morphological trait to body weight were all very significant (P<0.01).Head length, body height were eliminated from the variable data, because of no significance in multiple regression analysis. Total length was also kicked out from variable data because it was co linear with standard length. The regression equation was obtained as Y=-3048.127+220.925X₄+262.367X₆+33.776X₇+10.648X₂, in which body weight(Y) was used as the dependent variables and body width(X₄), interorbital width(X₆), length before anus(X₇), standard length(X₂) were as independent variables. Judged from the results of high correlation index(R² =0.900) it suggests that the main variables have been selected, among them the body width weighted the most(P=0.430)to the body weight, and it was key effective factor on body weight. In the selection process, four main morphological traits were considered as a whole,which provided essential theoretical basis and ideal measure for selective breeding of grass carp.