Abstract: Nine organochlorine pesticides(HCB, α-HCH, β-HCH, γ-HCH, δ-HCH, p,p'-DDE, p,p'-DDD, o,p'-DDT and p,p'-DDT)in water and soil samples are the priority pollutants to be determined in geological survey project. There are some analytical problems from complex sample matrix and some special properties of these pollutants when gas chromatography with electron capture detector was used. Based on the experiences in analysis of thousands of survey samples, how to diagnose and solve the problems were discussed from following four aspects:1) the relationship between solvent and analyte response, 2) sample matrix effect, 3) sample pretreatment, 4) instrument measurement. These experiences will help analysts to solve the analytical problems and obtain reliable analytical data.