Abstract: In the report, the Pinctada margaritifer populations from four distinct geographical regions, Haitang Bay (Hainan), Sanya Bay (Hainan), Chunyuan Bay (Hainan), and Weizhou Island (Guangxi), were selected, and the correlation and path analyses on shell morphological traits and total shell weight were conducted. One-way ANOVA, correlation analysis, stepwise regression, and path analysis, were used to investigate the geographic variation in morphometric-weight relationships. The results demonstrated that there are significant interpopulation differences among the four geographical population. The Haitang Bay population exhibited the highest shell width index, whereas the Weizhou Island population showed the minimum shell width index. The total shell weight index of the Weizhou Island population reached maximum values and that of the Sanya Bay population reached minimum. The correlation and path analyses results suggested that there were the geographical specificity in both correlation patterns and pathway effects on total shell weight. There were the significant correlations between the shell height and total weight in all populations, there were the most substantial direct effects of the shell width on the total shell weight. In Haitang Bay population, the determination coefficient of the shell width on the total shell weight was the highest (R²=0.261), with shell height contributing additional 0.015 through joint effects. In Sanya Bay population, the determination coefficient of the shell height on the total shell weight was the highest (R²=0.358), with shell width contributing additional 0.146 through joint effects. In Chunyuan Bay population, there were the prominent joint determination between shell width and hinge length (R²=0.161). In Weizhou Island population, the determination coefficient of the shell width on the total shell weight was the highest (R²=0.375), with shell width contributing additional 0.146 through joint effects. followed by combined effects of shell height and length (R²=0.158). Our findings provide the valuable insights for the selective breeding programs of Pinctada margaritifer, particularly in trait prioritization for shell mass improvement.