Abstract: 【Objective】 Urban street trees are an important part of urban forests. They help beautify cities, regulate and improve urban climate, purify the air, reduce the urban heat island effect, prevent dust, and reduce noise. Street trees play an important role in maintaining the urban ecological balance and improving the environment. Based on survey data of campus street trees at Nanjing Forestry University, the research gave evaluation of the ecological benefit for the study area.【Method】 i-Tree tool is a model that is specifically used for research on the benefits of urban forest systems. The i-Tree streets tool is a module that specifically evaluates the economic benefit of the urban street trees system. There is no limit on study size; it can be used to analyze a large research area or it can be used to examine a small area, such as a street. This tool explores the ecological functions of the urban street tree system and provides references for the management, planning, and planting strategies of urban street trees. Inventory data was surveyed for five regions of the campus(active, residential, teaching, living and administrative). Diameter and tree height were recorded for 2 350 trees and species composition was analyzed. Then the i-Tree module was used to build an ecological model. Five factors were calculated: energy-saving benefit, storm water retention benefit, air quality improvement benefit, CO₂ absorption benefit, and aesthetic benefit.【Result】 A total of 2 350 trees were examined during the field survey, which included 54 species belonging to 31 families and 49 genera. Most trees were deciduous and broad-leaved, including Prunus serrulata, Platanus hybrida,Liriodendron, Cinnamomum sp. and Ginkgo. These are the main tree species that constituted the street tree system, accounting for 48.5% of the total number of trees examined. The Prunus serrulata and Ginkgo were mainly planted in active regions, Platanus hybrida was mainly planted in residential regions, Liriodendron was mainly planted in teaching regions, and Cinnamomum sp. was mainly planted in living regions.The distribution of breast high diameter(DBH)of street trees on the Nanjing Forestry University campus shows that the main species(Prunus serrulata, Platanus hybrida,Liriodendron, Cinnamomum sp. and Ginkgo)had a DBH of 8 to 46 cm, with 441 trees(18.77%)in the 8 to 15 cm range, 1 132 trees(48.17%)in the 15 to 30 cm range, and 507 trees(21.57%)in the 30 to 46 cm range. In the active region, the majority of trees(n=247, 47.59% of the regional total)had a DBH of 8-46 cm. Most trees in the teaching region(341 trees), administrative region(207 trees), living region(243 trees), and residential region(171 trees)had a DBH of 15-30 cm. The average tree height was 23.16 m, and the tree height is normally distributed.The total eco-efficiency benefit of street trees in Nanjing Forestry University is available through the i-Tree tools software. The total value of the 2 350 street trees on the main roads of Nanjing Forestry University is 1 023 101.29 yuan. Improved aesthetics was the greatest benefit of campus street trees, accounting for 65.67% of total benefits. Interception of rainwater accounted for 17.05% of the total benefits and energy saved accounted for 13.02% of the total benefits. Reduction in CO₂ efficiency and improvement of air quality were the lowest overall benefits, accounting for 2.65% and 1.61% of total benefits, respectively. Among the five regions, the teaching region had the highest eco-efficiency benefits, accounting for 43.62% of the total, followed by the residential region which accounted for 19.43% of the total. The administrative region, active region, and living region accounted for 15.17%, 11.21% and 10.56% of the total, respectively.Contribution rates for various ecological benefits varied for different tree species. Four species contributed the most to the total ecological benefits:Platanus hybrida, Liriodendron, Cinnamomum sp. and Ginkgo, accounting for 21.97%, 18.09%, 14.50%, and 8.57% of the total, respectively. These four tree species accounted for 63.13% of the total ecological benefits. The administrative region had more high-quality trees. such as Populus and Ginkgo.【Conclusion】 i-Tree tools provides a way to analyze the benefit of street trees, which allows users to understand various ecological benefits and provides a reference for tree planting plans and reasonable road distributions. Tree species are rich and diverse on campus. In the living region, energy-saving and air quality benefits were the lowest compared to other benefits. Thus, we suggest planting Chinese ash and horse chestnut in this region. In the residential region, distribution of richness, evenness, total benefit, and average tree benefit were high relative to other regions. The main species in the residential region were Metasequoia, Gingko and Platanus hybrida, which are all highly economical efficient trees. The administrative region is relatively small and the roads are short; however, this region had the highest storm water retention benefit. This is because of the relatively high number of poplar trees in this region, as poplar trees had the highest individual benefit.