In order to guide the consumers to scientifically reduce the risk of pesticide residues intake when eating fruits and vegetables，the effects of pesticide residues on the nutritional quality of pakchoi were studied by applying 3 concentration levels of （1， 50， 100 μg/mL） pesticides including chlorothalonil， chlorpyrifos and fipronil to pakchoi. The effects of different washing and cooking methods on removing pesticide residues in pakchoi were compared. The results showed that the contents of water， soluble protein and nitrate all decreased firstly and then increased with the increase of the application concentration. There was no significant differences in the content of vitamin C and carotenoid between treatment groups（P>0.05）. The content of reduced sugar， calcium and phosphorus increased firstly and then decreased compared with the blank group. The content of crude fiber in the 100 μg/mL group increased. The removal effect for the all three pesticides was in the decrease order of detergent， alkali water and rice washing water soaking， and salt water and clear water. The thermal stability of chlorothalonil was poor. The removal percentages of three cooking methods for chlorothalonil were all above 94%. 60 ℃ blanching and 100 ℃ boiling for chlorpyrifos had lower removal effect， while hot oil stir-frying significantly improved the effect of removing（76.97%）. For fipronil hot oil stir-frying had the best effect of removing（82.68%）， followed by 60 ℃ blanching and 100 ℃ boiling. It is indicated that pesticide residues have a certain impact on the nutritional quality of pakchoi. Detergent washing， soaking in rice water and alkaline water， and hot oil stir-frying are effective methods to reduce pesticide residues in fruits and vegetables.