To study the effect of washing and cooking on residues of chlorothalonil, pyridaben, procymidone, cyhalothrin and fenvalerate in hot pepper, understand the changes of pesticide residues by processing, and to provide the basis for effective dietary exposure assessment.MethodsThe hot pepper samples were simulated in laboratory by soaking in pesticides polluted water. The samples were cleaned and cooked, and the pesticides residues were detected by GC-ECD. ResultsThe results showed that both washing and cooking had a great effect on pesticide residues, the general removal rates of these five pesticides were 54.12%-99.47%, 58.78%-95.95%, 55.74%-93.68%, 41.37%-95.67% and 44.71%-95.09%, respectively. The removal rates of the pesticides residues by different cooking methods were ordered as follows:frying>stir-frying>boiling. The longer the cooking time was, the more residues removed, but the removal rates didn't change significantly when the cooking time was longer than 2 min. ConclusionThe effect of pesticide residues removal in pepper by cooking was better than cleaning, and the effect was decided by hydrolysis, pyrolysis, melting and boiling point and vapor pressure of the pesticides.