Abstract: Influence of environmental factors on persistence of chlorpyrifos microcapsule suspension(CS) and emulsifiable concentrate(EC) against larva of Holotrichia parallela in soils were studied under ambient conditions using bioassay method.The results indicated that under the same conditions,persistence of chlorpyrifos EC decreased and the release of chlorpyrifos in microcapsules slowed down as soil moisture increased.Persistence of chlorpyrifos CS and EC in soil decreased as soil temperature increased.The active ingredient was trapped by organic soil,so the toxicity of chlorpyrifos CS and EC against H.parallela decreased,however its persistence extended.Among the results of different environmental factors tested,the persistence of chlorpyrifos CS in soil were all better than that of chlorpyrifos EC except when the organic content in soil was 1.0%,which showed that the persistence of chlorpyrifos CS and chlorpyrifos EC was similar.