Abstract: Objective The aim of this study is to reveal the genetic diversity on morphology traits of Eucommia ulmoides male flowers, to efficiently evaluate and utilize the E. ulmoides male flower resources and provide a theoretical basis for the breeding program. Method The main morphology traits, such as flower diameter, flower height, dry weight, moisture content, stamen length, stamen number and 1 000-stamen weight of 193 E. ulmoides germplasm male flowers were measured and the genetic diversity analysis was carried out. Result The results showed that there existed large variations in flower diameter, flower height, dry weight, moisture content and another 3 traits, and the variation coefficient ranged from 5.18% to 40.47%. High genetic diversity indexes were calculated in all traits and ranged from 1.825 0 to 2.012 3. Significant correlation was observed among traits, the correlation coefficient were 0.746 between flower diameter and flower height, 0.667 between flower height and dry weight, 0.831 between stamen length and 1 000-stamen weight, respectively. The results of cluster analysis showed that 193 E. ulmoides germplasms could be divided into 5 groups, the group Ⅲ including 15 samples was evaluated as excellent resources. The principal component analysis revealed that the first 3 principal components which accounted for 86.625% of the accumulated variance contribution rate were suitable for assessing the E. ulmoides male flower resources. Conclusion It is concluded that the 7 morphology traits of E. ulmoides male flowers had high genetic diversity and great potential for improvement, which could provide references for E. ulmoides breeding program and the utilization of male flower resources.