In this paper,based on the 2×2 table,a series of methods including association coefficient(AC),Ochai index(OI),Jaccard index(JI) and χ²-test were used to calculate and analyze synthetically the positive or negative interspecific associations and significances of 16 tree species and 32 shrub species in Qiaoshan Forest Region.Also,the analysis results were expressed by semi-matrix.The results indicated that:(1)There were significantly positive interspecific associations between Pinus tabulaeformis and Rhus potaninii,Quercus wutaishanica and Toxicodendron delavayi in the tree species.However,Robinia pseudoacacia was significantly negatively associated with other tree species.(2)Among the shrub species,Quercus dentata to Rhamnus davurica,Cotoneaster multiflorus to Viburnum schensianum,Ostryopsis davidiana to Rosa hugonis,Rhamnus davurica to Euonymus alatus,Lespedeza davurica to Viburnum schensianum,Lespedeza davurica to Spiraea chinensis showed a significant positive association,and Acer ginnala aggregated with most of the shrub species,while Ziziphus jujuba var.spinosa,Sophora davidii and Berberis purdomii showed negative associations with most shrub species.It is suggested that the relationships among the other woody species were weak since no significant associations were detected.(3)Based on the present results of interspecific association,4 ecological species groups of 16 tree plants were delineated.Meanwhile,5 ecological species groups of 32 shrub plants were also delineated in this area.Study of Interspecific association can also provide a reference for the protection and management of vegetation in the Loess Plateau.