Urban wilderness areas are crucial sources for biodiversity conservation in cities, providing high-quality ecosystem services. Chongqing, a typical mountain city, is home to numerous fragments of urban wilderness, primarily influenced by natural processes. This study focuses on urban wilderness forests in central Chongqing, through the community survey of 77 sample plots and 313 sample sites, analyzing the plant species composition, diversity, and regeneration capacity in different wilderness habitats，and exploring the correlations among plant species origins, seed dispersal methods, regeneration ability, and plant species diversity. The findings reveal that: (1) A total of 116 families, 307 genera, and 434 plant species were recorded. Native plants (79.03%) were abundant and spontaneous plants (89.17%) made up a significant proportion. The primary seed dispersal method was by animals (45.54%).. (2) 98.08% of the sample plots were able to regenerate autonomously, with 29 families, 53 genera, and 65 species of regenerating tree species. The species composition was similar to that of the tree layer, with a similarity index ≥0.50. The dominant species in the tree layer showed good regeneration capacity. Notable differences in the composition of regenerating tree species were found among various habitats, with the proportion of regenerating tree species and sampled plots being the highest in natural wilderness habitats. (3) Among different vertical layers, the plant species diversity indices (except except for Pielou’s evenness index) showed that tree layers＜shrub layers＜herb layers. Among different habitats, there were no significant differences in the Pielou’s evenness index for tree layers and Patrick’s richness index for herb layers across three habitat types (P > 0.05). However, visible differences were found in the plant species diversity indices for other layers (P < 0.01), with the highest diversity index recorded in the natural wilderness habitats. (4) The richness of native plants, spontaneous plants, animal-dispersed plants and regeneration-layer plants showed significant positive correlation with plant species diversity in all layers (P＜0.05). Based on the findings of the study, it is recommended to strengthen the classified protection of urban wilderness forests in mountainous cities. In the restoration of vegetation in mountain cities, it is advisable to select plants based on local conditions, promoting the creation of "near-natural forests" dominated by self-originating plants, indigenous plants, and animal-dispersed plants that can achieve sustainable, self-regenerating growth.