Abstract: Four quantitative traits (shell height, shell length, shell width and total weight) of scallop (Chlamys nobilis) at 3, 6, 7, 9 and 15 months were measured; phenotypic correlation of the 4 traits and their influence on total weight were analyzed. Results indicate that significant positive correlation is found among the 4 traits (P < 0.001). Shell length has a higher correlation coefficient to total weight than shell width. Path analysis shows that shell width has the smallest direct effect on total weight, while shell height has directer effect on total weight than shell length does at all ages except 7 months old. The determination coefficient of morphological traits to total weight varies from 0.910 to 0.943 and shows a similar trend with the path analysis. Regression equations between total weight and morphological traits at 6, 7, 9 and 15 months were also established. To improve total weight via morphological traits, the shell height should be selected firstly for scallops over 6 months old. The results provide a theoretical basis for determining selection index in genetic breeding of C.nobilis.