Although the beneficial effects of the agricultural extension of farmers’ biopesticide adoption have been largely demonstrated, the questions of what approaches can better extend biopesticides and how to improve the inefficiencies of biopesticide extension still need to be explored. In a survey of 1148 rice farmers in Hubei Province, China, the technology supply and demand theory was used to explain the low efficiency of biopesticide extension. The endogenous switching probit model was used to estimate the impact of biopesticide technology publicity, training, demonstration and subsidies on farmers’ adoption. The results show that biopesticide extension can promote rice farmers’ adoption probability by 10.3% ~ 11.7%. Among these methods, technology demonstration is currently the best way to extend biopesticides. Moreover, inadequate supply and demand of biopesticides are important for explaining the inefficiency of biopesticide extension in China. Extending biopesticides is better for farmers with smaller scales, younger ages, and lower education and for those who are cooperative members. Therefore, we should not only actively conduct biopesticide demonstration but also more importantly induce farmers’ biopesticide demand and secure the market supply of biopesticide products. These findings will provide useful guidance for biopesticide extension and pesticide reduction in China and other developing countries.