Abstract: In recent years, the plant water use efficiency has emerged as a prominent topic in both physiological and ecological research, gaining attention both domestically and internationally. This study used CiteSpace software to analyze 6 461 papers from three major Chinese journals and the Web of Science database, spanning from 1984 to 2024. The aim was to explore the differences in research focus between Chinese and international papers and to identify the evolution and future directions of research hotspots related to tree water use efficiency. The findings reveal that over the past 40 years, research in this area has advanced rapidly. Most of the keywords in both Chinese and international papers are consistent, with “water use efficiency” being the most frequently mentioned term. Chinese papers tend to concentrate more on the physiological changes in trees, with keywords like photosynthetic rate, transpiration rate, and stomatal conductance ranking higher. In contrast, international papers place greater emphasis on environmental impacts and the application of new research methods. In terms of keyword co-occurrence and clustering, Chinese papers are more focused on short-term physiological changes such as photosynthesis and transpiration. Meanwhile, international papers are more concerned with climate change and the long-term physiological changes in trees. This has led to the formation of distinct research groups on water use efficiency in both domestic and international contexts. Throughout the evolution of this research field, studies on water use efficiency and photosynthesis have been a consistent theme in Chinese journals. In contrast, international papers have continued to explore topics such as fruit quality, stable isotopes, climate change, and tree rings up to 2024. Regarding current research hotspots, keywords like drought stress and photosynthetic characteristics are particularly popular in Chinese papers. On the other hand, soil moisture and functional traits are highly prevalent in international papers, suggesting these areas hold significant research potential. This study provides a comprehensive overview of the current research status and development trends in tree water use efficiency, offering valuable insights for both domestic and international research communities. Additionally, it offers a reference for future research focused on using water use efficiency to evaluate tree health.