[Aim]  The aim of this study is to explore the inactivation method and verify the effectiveness of ultraviolet radiation on the Bombyx mori (silkworm) nuclear polyhedrosis virus. [Methods]  We evaluated the effectiveness of different UV irradiation methods, differing in power and irradiation distance and time, on the inactivation effect of the nuclear polyhedrosis virus. This was determined based on the survival rate of silkworm fed with the virus post-irradiation. We analyzed the inactivation effect on the P40 gene, a structural glycoprotein of the virus, using long chain PCR technology. Scanning electron microscopy was used to observe the structural morphology of the inactivated virus particles. Finally, we evaluated the impact of direct ultraviolet radiation on silkworms. [Results]  Silkworm exposed to 60 W of ultraviolet radiation at 40 cm for 60 min had a significantly higher survival rate compared to the virus control group, with survival rates of 63.33% and 45%, respectively (P=0.014 2). However, the survival rate of the 60 W exposure group was lower compared to the 15 and 30 W ultraviolet radiation exposure groups when the exposure distance remained at 40 cm, but the exposure time was extended to 120 min. At a radiation distance of 100 cm, the inactivation effect was poor, and there was no significant difference in the survival rate between the 180 min UV exposure groups and the virus control group(P=0.058 8). Long PCR detection using low concentration virus suspensions showed no obvious bands after 60 min of exposure to 15 W UV radiation at 40 cm. Conversely, high concentration virus suspensions required 480 min of irradiation under the same conditions to show no obvious band. Additionally, there was no significant change in the morphology of the virus particles compared to control virus group. Exposure to direct UV radiation had no significant effect on silkworms that were covered with a protective film. In contrast, the bodies of unprotected silkworms began to darken after 10 min of exposure at 40 cm and 30 min of exposure at 100 cm. Interestingly, the silkworm’s body color reverted and proceeded to cocoon normally after molting during the rest phase. [Conclusion]  The inactivation effect of UV irradiation on BmNPV was influenced by several factors, including UV intensity, irradiation distance and time, and virus concentration. As the irradiation time increased, the survival rate of the silkworm fed with the virus post-irradiation increased, and the level of nucleic acid destruction of the virus became more absolute. A UV irradiation distance exceeding 40 cm for or a minimum duration of 60 min inactivates the low concentration BmNPV while protecting silkworms from the adverse effects of UV radiation.