Abstract: Chlorpyrifos were widely used, the increasingly pesticide residue in vegetables were harmful to food safety. The effect of immersion time in water, washing after immersion, 1% NaHCO3, vinegar, dishwashing liquid and salt solution on cowpea were analyzed through gas chromatography. Different waterlogging time was helpful for the chlorpyrifos remove, which the removeale rate was 33.332%～70.718%;To clean the chlorpyrifos in cowpea with water flow after different waterlogging time, which the removal rate were 45.623%～69.924%;To remove the chlorpyrifos by flushing with 1% NaHCO3 solution, which the removal rate was 25.257%～49.299%;The eliminating effect of vinegar was good, the eliminating effect of dishwashing liquid was 17.588%～41.895%, and salt washing were not ideal. The detail for the best clean condition was to soak 15mins and before washing 2 mins, the removale rate was 42.651%～46.358%. The diet exposure assessment should take the processing in consideration to evaluate the pesticide residue on the diet exactly, which will be truly closed to the diet exposure volume, decrease the pesticide risk value.So will be positive to guarantee the diet safety.