This study focused on 44 elite individuals of Castanea mollissima Blume from Wangmo county， and applied genetic variation analysis， correlation analysis， principal component analysis （PCA）， and cluster analysis to characterize fruit phenotypic traits， and compared the distribution patterns of quantitative traits among different groups. Results showed that Wangmo chestnut involucres （spiny bracts） were predominantly ball-shaped with valvate dehiscence， most spine bundle colors were dark brown， reddish-brown was the most common nut color （40.91%）， and ellipse was the dominant nut shape （59.09%）. Among the 17 descriptive traits， the coefficient of variation （CV） ranged from 18.63% to 82.31%， with the diversity index spanning 0.40 to 0.97. For the 18 quantitative traits， the CV range was 6.69% to 39.58%， among which the CVs of nut width， nut height， nut shape index， seed extraction rate， kernel recovery rate， and moisture content of nuts were all less than 15%， the genetic diversity index ranged from 1.43 to 2.19. PCA showed that the cumulative variance contribution of the first five principal components reached 80.236%. Correlation analysis indicated that significant or highly significant correlations existed among most of the quantitative traits. Cluster analysis categorized the 44 Wangmo chestnut accessions into three distinct groups： Cluster I （small-fruit group）， Cluster II （medium-fruit group）， and Cluster III （large-fruit group）. Comparative analysis of quantitative traits among these three clusters revealed no significant differences in four traits—inner skin thickness， seed extraction rate， kernel recovery rate， and moisture content of nuts， while the remaining 14 traits exhibited significant differences. Both Cluster I and Cluster II showed a certain proportion of outliers in spine width， at 11.54% and 11.11%， respectively. Furthermore， seed extraction rate and moisture content of nuts in Cluster I， along with kernel recovery rate in Cluster II， displayed broad distribution ranges. Most indicators related to the size of the total bur and nut in Group III exhibited a significant upward distribution trend. This study elucidates the patterns of phenotypic diversity and characteristics of group differentiation in Wangmo chestnut germplasm， laying a solid foundation for the variety breeding of Wangmo chestnut.