Abstract: Based on the investigation materials during the period of 1998—2003, the shrub and grass species similarity and diversity in Pinus tabulaeformis forests of 10 regions around Beijing were compared and analyzed. The relationships of plant diversity in P. tabulaeformis forests and stand conditions using the software MatLab were analyzed, and protection measures are suggested finally. Generally, the shrub and grass in P. tabulaeformis forests at Shidu, Mutianyu and Yunfengshan are rich in species and high in similarity, and the species numbers in common in each two plots mentioned above are above 50%, while many peculiar species that cannot be found at other 9 regions exist at Labagoumen. As for plant diversity indexes, Baihuashan, Shidu and Labagoumen are a little higher, while Tanjiesi and Miaofengshan are much lower, with Songshan, Yunmengshan, Yunfengshan, Mutianyu and Shihuadong in the middle. Some endangered orchid species are found distributed in P. tabulaeformis forests with a clumped spatial pattern, but rarely appear in other forest types, indicating that P. tabulaeformis forests are ideal habitats for orchid plants. The principal components analysis reveals that the 9 factors relative to the distribution of P. tabulaeformis forests are all important, and among them 5 factors, i.e. the source of forests, forest density, slope direction, slope position and forest age are especially more important.