Abstract: An indoor simulation experiment was carried out to study photolysis and hydrolysis of emamectin benzoate in buffer solution,and degradation of emamectin benzoate in three different types of soils,black soil from Northeast China,red soil from Jiangxi and paddy soil from the Lake Taihu region.Results show that the photolytic half-life of emamectin benzoate in solution under the Xe lamp with optical intensity of 2 370 lx and ultraviolet radiation intensity of 13.5 μW·cm^-2 was determined to be 1.73 h.In solution with temperature 25 ℃ and pH 5.0 and 7.0 emamectin benzoate was hard to hydrolyze and its half-life was reckoned to be over 1 year.However,it was easy to hydrolyze in solution of pH 9.0 with a half-life being 45.3 days,which was shortened in solution of higher temperature.The half-life of emamectin benzoate in red soil,black soil and paddy soil was 16.3,41.5 and 91.2 days,respectively,which was affected mainly by biodegradation and hence the content of soil organic matter.