Wild clams of Meretrix meretrix and Cyclina sinensis were collected from intertidal flats of Shuangtaizi estuary during low tide in 2016. Morphometric traits including shell length (SL), shell height (SH), shell width (SW), and total body weight (TW) of the clams were measured. Correlation, path, and regression analyses were conducted to evaluate the relationship between morphometric traits and total body weight and determine the optimal indices for artificial breeding of M. meretrix and C. sinensis. Significant differences in correlation coefficient among various characteristics were found. Shell height and SW showed the strongest influence on total body weight. The optimal regression equation of the measured traits was established in both clams by using a stepwise regression method: TW = –27.404 + 0.948 SW + 0.422 SH + 0.291 SL for M. meretrix and TW = –36.965 + 1.107SH + 0.564SW for C. sinensis. These results provide baseline information for selective breeding and conservation management of the two commercially important clam species in Shuangtaizi estuary.