Based on the scale of urban park green space system and the scale of urban park plant community in Huainan City, the carbon sequestration capacity and benefits of urban park green space landscape pattern and internal plant community were analyzed using landscape pattern index method and i - Tree model, and the key ways to promote the carbon sink benefits of park green space were put forward. The results show that: (1) There are few specialized parks in the park green spaces of Huainan City but they have a relatively large area, while there are many garden parks with a small area. The number of comprehensive parks and community parks is small, and the spatial distribution is uneven. The aggregation index (AI), landscape shape index (LSI) and average shape index (MSI) are small, resulting in less carbon sink benefit. (2) Most of the tree species are of medium and small diameter classes, which are planted recently, so their carbon sink capacity is not fully exerted. (3) The annual carbon storage of 1 010 trees in the research area is 203. 42 t, with a total benefit of 187 146. 4 yuan; the annual carbon sequestration is 15. 62 t, with a total benefit of 14 370. 4 yuan. The tree species with the higher per-plant benefits are Styphnolobium japonicum, Sapindus saponaria, Liriodendron chinense，while those with lower per-plant benefits are Ginkgo biloba and Acer palmatum.