The photodegradation of fenarimol in various solvents under 3 kinds of light sources was studied.In hexane,acetone,methanol,acetonitrile,and isopropanol,the photolytic rates of fenarimol were rapid.The halflives of fenarimol were 8.73,288.81,26.87,4.25 and 16.54 min respectively under high pressure mercury lamp;4.25,10.65,3.87,2.46 and 3.09 h respectively under UV light,4.88,20.62,14.29,3.30 and 13.83 h respectively under sunlight.It was found that the photolysis of fenarimol was rapid when it was irradiated by sunlight.The photolysis of fenarimol in water could be restrained by acetone.The photoquench rate was found distinctly related to quantity of acetone.The photolytic mechanism was also discussed.The photolytic rate of fenarimol has connection with the absorption spectrum of solution.