The removal of four kinds of organophosphorus pesticides including dichlovos,malathion,dimethoate,and chlopyrifos by alkaline water(pH 10.5 and 11.5),ozonated water and tap water were investigated in lettuce.The content of residues of pesticides was performed by GC.The results indicated that alkaline water could significantly lower all four pesticides.The pH values,and treatment time influenced the treatment.The alkaline water washing at pH 11.5 performed best.The removal rate increased with the decreased initial concentration of the pesticides.Furthermore,15 min washing was enough for the effective degradation of pesticides.