Abstract: Tomicus piniperda is a kind of trunk attacking pest distributed all over the world and causes serious damage to Pinus species.In recent years,the bark beetle destroyed thousands hectares of Pinus yunnanensis forest in Yunnan Province.The field work was carried out at Changhu Forest in Shilin County and Xiaobailong Forest in Yiliang County.Attacking habits of T.piniperda during trunk attacking period were studied through periodic sample trees cutting and tree trunk damage investigating method.