Abstract: Trees are not only an indispensable part of the ecological environment, but also the main factors that undertake the cooling and humidification effect in urban green space. Microclimate is the most closely related to human beings, and it is also the easiest to adjust by artificial means. In this paper, the CiteSpace software was used to carry out knowledge graph visualization analysis of relevant literature on the relationship between trees and microclimate from 1990 to 2020. The conclusions were summarized as follows:（1）The international research trend on the relationship between trees and microclimate was on the rise, and it showed the trend of refined thematic research;（2）In terms of research strength, the United States and China had made great contributions to this research field. Although China started late, the number of published articles and the influence of literature were also increasing year by year, which was an important force in this research field. The United States occupied an important position in the number of articles and institutions. The research started early, and it was in a leading position in the study of the relationship between trees and microclimate. There were many exchanges and cooperation among the authors, and their research topics were different, forming an obvious cooperative group. These research forces laid a theoretical foundation for the study of the relationship between trees and microclimate.（3）The research on the relationship between trees and microclimate experienced three development stages: slow development stage, exploration stage and high growth stage. The research hotspots in each stage were different, and the current research hotspots mainly focused on urban human settlements environment.（4）The development focus was different at home and abroad. Foreign research object tended to be macro ecology, and the communication between research institutions was closer. Domestic research objects tended to focus on micro-urban environment, with concentrated research institutions but few contacts. It is the development trend of future research to strengthen international academic exchanges and inter-disciplinary exchanges.