Urban green space is an important natural and heterogeneous component of urban landscape, which plays an important role in providing urban ecosystem services and improving residents' well-being. As an important component of urban green infrastructure, the health status of urban trees directly affects urban ecosystem services and the quality of human settlement environments. The accelerated urbanization process leads to the loss of ecological land, and the lack of reasonable maintenance and the disturbance of extreme natural conditions pose a serious threat to the health of urban trees, affecting the effective development of the ecological, social and economic benefits of trees. In order to find the risk and influencing factors of urban tree health, a tree health index system was constructed from 4 dimensions and 12 indexes. Based on the survey of 117 sample plots in core urban area of Urumqi, through analyzing the tree composition, structure, association, health status and its influencing factors, the differences of tree health are revealed in different functional zones. The purpose is to provide theoretical basis and data support for tree health protection and sustainable management of urban green space in the study area, which is of great significance to play the landscape service function of green space and improve the degree of urban ecological civilization. The results show that:(1) the average ratio of trees to shrubs in core urban areas in Urumqi is 8.3:1; especially, the tree species diversity, inter and intra correlation of urban green species are low. Elm (Ulmus spp.) accounts for 43.87% of the total urban trees, of which Ulmus pumila accounts for 22.62%, which is the main dominant tree species. (2) There are some differences of the health status between different Elm species. The overall health status of the Elm species elaborates the characteristics of Ulmus densa > Ulmus laevis > Ulmus pumila > Ulmus pumila cv. pendula. (3) The tree health presents heterogeneity in different urban functional zones, which main public parks and residential areas are higher, while roadside and schools are relatively lower. The redundancy analysis further reveals that ground pavement, tree configuration structure, growth space and diameter at breast height (DBH) have the greatest contribution on the tree health. In the future, optimizing urban tree habitat conditions, improving species richness, strengthening conservation of ancient trees and improving landscape planning and management level are important measures to maintain and improve the health status of urban trees in arid land oasis cities.