This paper studied the impacts of different dose ultraviolet irradiation (254 nm, UVC) on the sperm motility and longevity of Acipenser baerii. Ultraviolet irradiation had significant impacts on the sperm motility, its fast motion time, and longevity. With the increasing dose of ultraviolet irradiation, the sperm motility decreased rapidly first, increased rapidly then, and decreased rapidly again. The sperm fast motion time had the similar variation trend as the sperm motility, but the sperm longevity kept decreasing with increasing dose of ultraviolet irradiation. When the ultraviolet irradiation dose increased to 288 mJ x cm(-2), the sperm fast motion disappeared; when the ultraviolet irradiation dose increased up to 324 mJ x cm(-2), the sperm had no motility and died. According to the "Hertwig effect", the optimum ultraviolet irradiation dose for inactivating A. baerii sperm was 216 mJ x cm(-2).