[Objective] To investigate morphological diversity of 15 populations of Mentha haplocalyx Briq. from different habitats in China, so as to provide a scientific basis for breeding selection in future work. [Method] 9 indexes describing morphological diversity of Mentha haplocalyx Briq. including plant height, leaf length, leaf width, petiole length, leaf pairs, stem thickness, branch number, branch length and node number were investigated, whose experimental data was analyzed by variance analysis, correlation analysis, principal component analysis and clustering analysis. [Result] The morphological variation coefficient of 9 indexes was 13.79%-83.65%, among which leaf pairs and branch length exceeded 75%. There were some correlations among external morphology, including extreme significant positive correlation (leaf width and leaf length, petiole length and leaf width, leaf pairs and stem thickness, branch length and leaf pairs, stem thickness, node number and leaf pairs) and extreme significant negative correlation (branch length and leaf length, node number and leaf length). Based on principal component analysis, 9 morphological indexes were summed up to 3 principal components whose cumulative contribution accounted to 90.47%. The 15 populations were divided into 2 groups by clustering analysis, one group included populations collected from Jiangsu Dongtai, Anhui Fuyang, Anhui Taihe, Zhejiang Hangzhou which were featured by tall plants, large leaves and many branches; apart from the above populations, the remaining 11 populations were divided into the other group which were featured by short plants, small leaves and few branches. [Conclusion] Owing to China was vast in territory, polymorphism of Mentha haplocalyx Briq. population habitats resulted in large variability in external morphology, leading to abundant genetic diversity. [Objective] To investigate morphological diversity of 15 populations of Mentha haplocalyx Briq. From different habitats in China, so as to provide a scientific basis for breeding selection in future work. [Method] 9 profile describes morphological diversity of Mentha haplocalyx Briq. Including plant height, leaf length, leaf width, petiole length, leaf pairs, stem thickness, branch number, branch length and node number were investigated, whose experimental data was analyzed by variance analysis, correlation analysis, principal component analysis and clustering analysis. [Result] The morphological variation coefficient of 9 indexes was 13.79% -83.65%, among which leaf pairs and branch length exceeded 75%. There were some correlations among external morphology, including extreme significant positive correlation (leaf width and leaf length, petiole length and leaf width , leaf pairs and stem thickness, branch length and leaf pairs, stem thickness, node number and leaf pairs) and extreme si gnificant negative correlation (branch length and leaf length, node number and leaf length). Based on principal component analysis, 9 morphological indexes were summed up to 3 principal components accounted for 90.47%. The 15 populations were divided into 2 groups by clustering analysis, one group included populations collected from Jiangsu Dongtai, Anhui Fuyang, Anhui Taihe, Zhejiang Hangzhou which were featured by tall plants, large leaves and many branches; apart from the above populations, the remaining 11 populations were divided into the other group which were featured by short plants, small leaves and few branches. [Conclusion] Owing to China was vast in territory, polymorphism of Mentha haplocalyx Briq. population habitats resulted in large variability in external morphology, leading to abundant genetic diversity.