Abstract: In this paper, an installation of UV disinfection was designed, and its efficacy against the Fusarium oxysporum f.sp.cucumerinum which is a kind of root-infecting pathogens, was tested in lab. The cultures of Fusarium oxysporum f.sp.cucumerinum were grown in potato dextrose and introduced artificially to a tank that contained enough water. By examining the number of spores grown in the plate of potato dextrose agar before and after being disinfected, it was found that Ultra-violet radiation is effective against Fusarium oxysporum f.sp. cucumerinum. The pathogens were totally killed when the water(T10=96.65%) flowed at 36L/min and the pathogen concentration was 6.87×102conidia/ml. Even if the concentration of pathogen was 1.14×105conidia/ml, the spores could not survive when the water(T10=95.42%) flowed at 36L/min. And when the water(T10=11.58%) flowed at 7.9 L/min and 35L/min, the disinfection rate was 81.31% and 50%, respectively.