Abstract: The residual dynamics of Malathion in rice plant, soil, water samples were determined by NP Gas Chromatography. Samples were extracted with acetone and dichloromethane, followed by determination using NP GC. The result showed that the recovery rate was from 96.12% to 107.28% for the rice plant, 78.5%～91.7% for the soil, and 80.3%～96.5% for the water samples with coefficients of variation of 6.43%～8.71%, 6.39%～9.15% and 3.23%～6.76%, respectively. The minimum detectable limits of the method were 1.79×10-11g. The minimum detectable concentration of Malathion was 0.009mg/kg for rice plant, 0.020mg/kg for soil samples and 0.005 mg/kg for water samples. The degradation half-life of Malathion within the rice plant, soil and water samples, two experiments conducted in Hunan and Zhejiang Province in 2006, was 1.60～3.77 days, 3.76～3.97 days and 0.90～1.02 days, respectively. Similarly, the degradation half-life of Malathion within the rice plant, soil and water samples, two experiments conducted in Hunan and Zhejiang Province in 2007, was 2.87～3.04 days, 8.10～10.70 days, 0.46～1.07 days, respectively. It was found that Malathion degrades faster in water samples than in rice plant and soil.