Abstract: In recent years,a lot of trees of Pinus tabulaeformis forest have been found to be withered or dead in several regions in Xiaojin county and this phenomenon has a further spreading tendency. In this paper,analysis is made of pests and site conditions of P. tabulaeformis. The results have shown that the withered reason of P. tabulaeformis in Xiaojin is the result of the comprehensive function of pests and site conditions. Because of poor site conditions in Xiaojin,P. tabulaeformis growth is worse than other tree species,thus giving the opportunity for the invasion of pests,such as blight,pine needle rust,bark beetles and longicorn beetles,and causing the growth of P. tabulaeformuis to decline and even die. Therefore the effective measures should be adopted to control these potential disasters and strengthen the tending of the stand and the monitoring of pests.