Effects of seven kinds of pesticides and five kinds of surfactants on photodegradation of fungicide fenarimol were studied on glass surface under sunlight and high-pressure merury lamp(HPML).Under HPML,three of the pesticides,namely chlorothalonil,fenpropathrin and fenvalerate effected the photodegradation of fenarimol,and the quenching rate were 22.58%,39.53% and 26.54%,respectively.The pesticide phoxim showed strongly effect,and the quenching rate reached 183.2%,prolonged its half-life up to 35.9min.Vinclozolin sensitized the photolysis of fenarimol,the sensitizing rate reached 38.72%.Two kinds of surfactants,namely Tween-60 and SDBS,were strongly sensitized the photolysis of fenarimol.But surfactant SDS quenched the photolysis of fenarimol.