Under the new normal of the economy, the planted vegetation in garden construction with faces a series of problems, such as high management and maintenance cost and landscape homogeneity. The demand for transformation to urban green space with low maintenance costs and sustainable green space is increasingly urgent. Previous studies have recognized the necessity of giving preference to garden plants with strong ecological adaptability and common maintenance cost requirement. At the same time, there is still no complete optimization system for low-management plants. Therefore, based on the spontaneous plants in Nanjing urban park, the species composition, growth status, and ornamental value of automatic plants in three habitats (understory, grassland, and waterfront) are investigated with the methods of Analytic Hierarchy Process (AHP), questionnaire survey and expert consultation. The landscape value of spontaneous plants in Nanjing urban parks is rated and graded, and the optimal selection system of automatic plants under low maintenance management is established. This study provides a theoretical framework for the optimization system of low-cost management and maintenance plants in urban parks as well as references for other cities in China to construct garden plant landscapes.