[ Objective ] With Cupressustorulosa, Cinnamomum camphora and Cyclobalanopsis Oerst as test materials, the paper studied the effects of different non- host plants on olfactory responses of Tomicus yunnanensis. [ Method ] The needles of Pinus yunnanensis were mixed with the leaves of Cupressustondosa, C. cam- phora and C. Oerst according to the ratios of 0 g ： 6 g, 1 g ： 5 g, 2 g ： 4 g, 3 g ： 3 g, 4 g ： 2 g, 5 g ： 1 g and 6 g ： 0 g, and the mixtures were put in the re- spanse arm of Y-tube olfactometer as odor source to observe the olfactory behavior of T. yunnanensis, the empty arm was set as control. [ Result ] When the needles of P. yunnanensis were mixed with the leaves of non-hest plants according to the ratio of 1 g ： 5 g and 2 g ： 4 g, they had less difference on attractive rate to T. yun- nanensis compared with complete P. yunnanensis needles in mixture （ratio： 6 g ： 0 g）, and the maximum difference was 14%. When the needles ofP. yunnanen- sis were mixed with non-host leaves according to the ratio of 1 g ： 5 g, 2 g ： 4 g, the attractive rate to T. yunnanensis decreased compared with complete P. yun- nanensis needles in mixture （ ratio： 6 g ： 0 g）, and the decrease value in maximum was 40%. [ Conclusion] When the ratio of non-host plants was relatively small in mixed leaves, non-host had less impact on olfactory responses of T. yunnanensis. As the proportion of non-hest leaves gradually increased, the attractive rate of leaf mixtures to T. yunnanensis was gradually small. The results could provide reference for determination of mixed ratio in construction of mixed forest and the de- velopment of botanical attractive and repellent of T. yunnanensis.
