Abstract: The daily-variation of microclimate and the function of increasing temperature and decreasing humility by woodland are analyzed by using meteorological data collected in Jiading,Shanghai from June to Septemper,2003 in this paper.And also the comprehensive index which impacts pests is analyzed too.The results show that amounts of spots beaten by poplar white leafminer(Leucoptera susinella),small prominent(Micromelalopha troglodyta),Japanese lawn grass cutworm(Sidemia depravata),and Homona magnanima have a close relationship with the temperature at 02:00 in the morning,and also have a close relationship with relative humility.