This study selected 60 accessions of Camellia sinensis var. assamica from 7 regions in Hainan Province as research materials. It systematically examined 28 phenotypic traits (comprising 19 qualitative traits and 9 quantitative traits) and comprehensively assessed their morphological variation and genetic diversity through diversity analysis, correlation analysis, principal component analysis, and K-means clustering. The findings indicated that the accessions of Camellia sinensis var. assamica in Hainan exhibited rich phenotypic variation with an average diversity index of 4.13 for the 9 quantitative traits and 4.29 for the 19 qualitative traits. Among these traits, the variations in bud length, the length of one bud with two leaves, and leaf base were especially notable. There were intricate correlations among the traits. Leaf length was significantly and positively correlated with the number of leaf veins and bud-leaf trichomes, whereas leaf shape was negatively correlated with leaf tip, leaf tooth density, and sharpness. The cumulative variance contribution rate of the first 9 principal components extracted by principal component analysis was 76.77%, which respectively represented key trait combinations such as leaf morphology, tree structure, and fruit shape. The clustering analysis classified the 60 accessions into 5 phenotypic groups, and the characteristics of each group differed significantly, which were associated with ecological adaptability. The phenotypic database established in this study provided an important morphological foundation for the conservation of Camellia sinensis var. assamica germplasm resources in Hainan, variety breeding, and mechanized production in tea gardens, such as the optimization of pruning equipment and the design of conveyor belts to prevent damage.