To explore the growth characteristics of Meretrix meretrix in ponds in various months, the shell length (SL), shell width (SW), shell height (SH), and body weight (BW) of M. meretrix at 10, 15, and 20 months of age were measured. The effects of morphological traits on body weight were discussed through correlation, path, and multiple regression analyses. The results showed that the morphological trait with the highest correlation coefficient at 10 and 15 months was SL, and the morphological trait with the highest correlation coefficient of 20 months was SW. Path analysis showed that SL, SH, and SW had the greatest direct impact on the body weight of M. meretrix at the age of 10–20 months. The multiple regression equations established by BW and morphological traits were BW₁₀ = ? 2.976+0.100SL+0.140SW+0.101SH (R² =0.969); BW₁₅ = ?12.176+0.085SL+0.441SW+0.415SH (R² =0.957); and BW₂₀=?21.506+0.255SL+1.098SW+0.152SH (R² =0.920). The allometric growth equation showed that M. meretrix followed different growth laws at different ages: positive allometric growth at 10 months, isokinetic growth at 15 months, and negative allometric growth at 20 months. The results showed that the morphological traits affecting the live weight of M. meretrix changed significantly with the increase in the age of M. meretrix. SL and SH had the greatest impact on BW at 10 and 15 months, respectively. However, with the increase in the age of M. meretrix, the influence of SW on BW increased, which was the quantitative trait index that had the greatest impact on the body weight at the age of 20 months. The results could provide a theoretical reference for the breeding of M. meretrix.