Abstract: A series of microcapsules were prepared with urea-formaldehyde resin (UF)/chitosan (CS) as the shell,and avermectin xylene solution as the core.The chemical structure,composition and morphology of the microcapsules were characterized by FT-IR,GSD and SEM,and the sustained-release properties were studied.The results show that the formaldehyde introduced in the pre-polymerization stage of the polycondensation can increase the content of chitosan in shell layer.Therefore,the encapsulation rate of avermectin and sustained-release rate of the microcapsules are improved.Under optimized preparation conditions,the particle size of MCP is 7.14 μm and encapsulation efficiency is more than 70%.