Abstract: The method of the nested analysis，principal component analysis，cluster analysis and other statistical methods were adopted to reveal the pattern and degree of morphological variation of 14 leaves phenotypic characters from 150 individuals of 6 Ulmus lamellosa natural populations. The results showed：（1）All the 14 phenotypic characters showed a significant or very significant differentiation within and among populations，indicating there is a wealth of variation.（2）The coefficient of variation CV of 4 morphological indexes（vein，tooth of the widest part，blade and petiole）were 15.425%，23.731%，25.446% and 45.168% respectively. The stability of leaf veins was the highest，while the leaf petiole was the lowest. （3）The mean phenotypic differentiation coefficient V_ST among populations was 28.104%，far less than that of within populations（71.896%），which indicated that the variation mainly occurred within populations.（4）The phenotypic characters of Ulmus lamellosa showed gradient regularity. The leaves，petiole width and leaf thickness became smaller gradually with the increase of latitude.（5）The 6 populations of Ulmus lamellosa gathtered into 3 clustes based on Euclidean distance.

Key words: Ulmus lamellosa, phenotypic diversity, natural population