The pattern and dynamics of forest community species diversity have always been the research focus of ecology, and the change of species diversity in the succession process of abandoned plantations is also worth studying. The Chinese fir (Cunninghamia lanceolata) is one of the most widely cultivated woods with the highest economic value in the southern forest region of China. This plantation usually has a simple community structure, low species diversity, and poor stress resistance. As for the community in subtropical area, many scholars have studied and discussed the community characteristics of the Chinese fir forests in different forest ages or different thinning intensities, but how the number of the Chinese fir in the community affects the plant species diversity is lack of research so far. In this study, 6 one-hectare long-term dynamic monitoring plots were established at the abandoned Chinese fir forest with different thinning intensities and abandoned time in four nature reserves of Zhejiang Province. Each woody plant with DBH (diameter at breast height) ≥ 1 cm was investigated, and the species name, DBH, height and coordinates were recorded. The community species diversity (species richness, Simpson index, Shannon-Wiener index and Pielou's evenness index) was investigated at the scales of 10 m×10 m, 20 m×20 m, 50 m×50 m, and 100 m×100 m. The distribution pattern and correlation between the number (abundance and relative abundance) of the Chinese fir and species diversity were analyzed. The results showed that the higher the thinning intensity of the Chinese fir forest before abandonment, the higher the species diversity of the community after succession. Under the same thinning intensity, the species diversity firstly increased and then decreased during succession. When the sampling scale was less than 100 m×100 m, the number of the Chinese fir was negatively correlated with species diversity. Under the scale of 100 m×100 m, only the relative abundance of the Chinese fir was negatively correlated with the three diversity indices (Simpson index, Shannon-Wiener index and Pielou's evenness index), but there was no significant correlation between the abundance of the Chinese fir and species richness. The values of the three diversity indices in each community were consistent, but had no correlation with species richness. In a word, when the relative abundance of the Chinese fir was less than 30%, the community usually had relatively high species diversity.