This article empirically analyze the preference and willingness to pay in biological pesticide by using the selection experiment and Mixed logit model.The results show that: (1) Most tea farmers are willing to try to use biological pesticides, and prefer the pesticide properties of "shortening safety interval", "not using in advance" and "not developing drug resistance".However there is preference heterogeneity in "shortening safety interval" and "targeting prevention". (2) Tea farmers with small planting area, long years of education, and high awareness of chemical pesticide hazards tend to choose biological pesticides. (3) Tea farmers are willing to pay 16.974, 22.250 and 11.272 yuan / mu / year respectively for the optimization of the above three attribute levels. (4) The actual payment cost of biological pesticides is higher than the willingness to pay the total cost of its various attributes.Attention should be paid to the externalities of biological pesticides.