In the study, an isolation of soil particles in different sizes in terms of the dry sieve method and gravitational dry sedimentation meshed was carried out to explore the relationship among the contents of DIET and BHC, the size of soil particle and the content of organic matter in different types of topsails in Beijing region during windy and dusty seasons. The results obtained show that DDT and BHC remaining in the soils were mainly distributed in the soil particles of <0.25mrn in size and the amounts of DDT and BHC in <0.05 mm soil particles that could be earily floated by air current accounted for 41-89 and 30-81 percent, respectively, of the total amounts in the original topsails. It was found that within a certain size range, the smaller 21ae size of soil particle, the higher the contents of DDT and BHC were, and that the contents of DDT and BHC were positively correlated to the content of organic matter (P<0.01) and that the proportions of DDT, BHC and some of their metabolites and isomers in soil particles changed with the soil size.