In Robit Bata, fruits, vegetables, and cash crop chat are cultivated both in wet and dry period. During growth period, organochlorine pesticides particularly endosulfan α and β, were sprayed frequently within one up to two-week interval and these practice result to increase the amount of non-degradable pesticide residue on the leaves of chat and vegetables. This leads to environmental pollution and affects human’s health. In this thesis the residual concentration, the degradation rate, the effect of seasonal variation on the degradation rate of pesticide, the effect of repeated application of pesticide and the health risk assessment of pesticide residue were analyzed. Based on experimental design, for both dry and wet season samples were prepared by QUCHERS extraction method. Then concentration of pesticide residue was analyzed in gas chromatography with micro ECD detectors. According to gas chromatogram G-µECD result in both dry and wet season the residual concentration of endosulfan alpha and beta is decrease with time. The analysis of degradation and persistence ability of endosulfan alpha and beta were investigated by using degradation rate constant and half-life of degradation according to this comparison, the degradation rate constant of endosulfan alpha is high and the half-life is low related to endosulfan beta in both cycle and season [for dry season 19hr<78,22hr<105hr and for wet season 17hr<53hr,20hr<66hr]. Therefore, endosulfan alpha is highly degradable and less persistence to the environment than endosulfan beta. Degradation rate constant of endosulfan alpha during cycle one is higher than rate constant of cycle two in both dry and wet season [3.64*10-2 > 3.15*10-2;8.8*10-3 > 6.6*10-3 and 4.07*10-2 >3.4*102;1.3*102>1.3*10-2] means the remaining concentration of first cycle leads to increase the first concentration of second cycle therefore repeated application of pesticide affect the residual. In this thesis the effect of seasonal variations on the degradation rate of pesticides were also analyzed by comparing the degradation rate constant and half-life of degradation between dry season and wet season. According to the result, the degradation rate constant of wet season is higher than the degradation rate constant of dry season Therefore; pesticides are more degradable in wet season than dry season.