Abstract: Based on the investigation data from the sampling plots of Pteroceltis tatarinowii secondary forest in limestone mountain area of north Anhui, and by the methods of space substituting time and O_ring statistics, this paper studied the diameter-class structure and the spatial distribution pattern and association of the P. tatarinowii population at its different development stages. In the plots, the diameter-class structure of P. tatarinowii population presented an invert “J” shape, and the individuals, mainly seedlings and saplings but fewer medium and mature trees, were distributed in each diameter-class, showing a stablegrowth type of the population in different habitats. The seedlings, saplings, and medium trees exhibited an obvious clumped distribution at some small spatial scales, and the aggregate intensity of Huangcangyu population was significantly higher than that of Xiangshan population. With the increase of spatial scale, the individuals tended to distribute randomly. The individuals at mature stage all exhibited random or approximately uniform distribution. The spatial association of the population at different development stages was mainly at medium and small scales, and, with the increase of the scale, the spatial association turned to be not significant. It was suggested that the diameter-class structure and spatial distribution of the P. tatarinowii population were mainly affected by the habitat heterogeneity, population’s itself biological properties (especially clonal reproduction), and human disturbances.