Abstract: The toxicity of As varies with its form and valeuce, its toxic order is A8H3> A. ( 111 )>A5 ( V )>organic As. Although the toxicity of organic As is less than that of inorganic As, half or 1/3 of total As in the soils applied with pesticide are organic As. In order to assess properly the environmental pollution caused by As, it is necessary to determine the amount of total As, inorganic As and organic As in the environment. Organic As was determined by the differences between total As and inorganic As in this study. This method is simple and feasible. The recovery rate of this method is 82-92%, and the detection limit is 0.1 ppm.This method was used to determine more than 60 samples in pesticide-applied fruit garden. Good social and economic benifits were achieved from the analysis. The method provides scientific bases for proper assessment of organic As in environmental pollution.