This study took 3 mountain ranges (Wumeng mountain, Miaoling mountain and Wuling mountain), 19 walnut and iron walnut populations,and 245 individual plants in Guizhou Province as the research materials,and analyzed the diversity, correlation, clustering and variation of 29 nut phenotypic traits, in order to reveal the phenotypic genetic diversity level of walnut resources in Guizhou, and provide a basis for the conservation and utilization of walnut resources in Guizhou and the construction of core germplasm. The results showed that: (1) the Simpson index of 18 phenotypic quality traits of 245 germplasm resources of walnut and iron walnut were 0.26-0.82, and the Shannon-Wiener index was 0.12-1.79. The shape of walnut leaflet was diverse, and parietal leaf degeneration was prone to occur, Nut shell surface characteristics, nut shape and Walnut skin color were rich in diversity. (2) The coefficient of variation of nut phenotype is 3.32%-47.67%, the average is 21.28% and the difference is significant (P<0.05), the coefficient of variation between populations is 9.42%-31.61% and the difference is significant (P<0.05). Intra-population and inter-population variation is the source of walnut phenotypic diversity. However, the differences in nut traits between populations were significantly higher than those within population, indicating that inter-population variation was the main source of nut phenotypic variation in this region. (3) The phenotypes of walnuts in the three mountain regions have different degrees of variation, among which, the Miaoling Mountain had a low degree of walnut phenotype variation, while the Wumeng mountain had a high degree of walnut phenotypic variation. UPGMA clustering results showed that the 19 walnut populations were divided into three categories according to the Guizhou Mountain range, indicating that the square European distance of the nut phenotypic traits of Guizhou walnut resources showed a positive correlation with the geographical region or climatic conditions. It is believed that Guizhou is rich in walnut germplasm resources and has high phenotypic diversity, and its phenotypic variation mainly comes from inter-population variation.