Abstract: The discovery of new agrochemicals is a time-consuming, costly and complex systematic project. The design of new agrochemical molecule is initial and the most important part of the project. In this review, the traditional design methods of agrochemicals were briefly summarized, and a new method, the plug-in molecules method, was presented on the basis of the practice of our group. Arylpyridinylmethanone and aryloxypyridinylethanone were used as two representatives of plug-in molecules. Their design and application in pesticides discovery were sketched out. The main advantage of this new method is that the pharmacophores and functional groups were modularized, which facilitates rapid derivation and screening, shortens the period of new agrochemicals discovery and meets the demand of fierce competition.