Abstract: Tar spot disease is a widespread foliar disease in broadleaf tree plantations. Its pathogens are highly diverse, and their disease symptoms and morphological characteristics are often similar, and the ascospores within the ascomata collected in the field are often underdeveloped, making morphological identification challenging. Based on morphological characteristics and multi-gene phylogenetic analysis, this study identified the pathogen causing tarspot on Acer buergerianum collected from Chuzhou and Hefei cities in Anhui Province as Rhytisma annuliforme. These results provide a theoretical basis for the identification and control of pathogenic fungi causing tar spot disease in Acer species.