The BSD Blind Spot Monitoring System is an in-vehicle safety assistance system that can help drivers monitor blind spot areas during driving and reduce potential safety hazards caused by blind spots. It usually uses sensor technology such as camera or radar to monitor the blind spot area around the vehicle in real time, and prompts the driver to pay attention to the existence of the blind spot area through sound or vision. In severe weather conditions such as heavy fog and heavy rain, the driver's line of sight will be greatly affected, and the blind spot will also increase. At this time, the BSD blind spot monitoring system can play an important role in helping drivers better perceive the surrounding environment and reduce safety risks caused by blind spots. To sum up, the application of BSD blind spot monitoring system in blind spots such as heavy fog and heavy rain can greatly improve driving safety and reduce accidents. It is an important vehicle safety assistance system, which plays a positive role in promoting the driver's safe driving.