With the rapid development of intelligent assisted driving, intelligent connected vehicles, while enhancing the level of driving intelligence, are increasingly attaching importance to safety protection design. This article first provides a brief overview of intelligent connected vehicles, then analyzes the security threats they face from three dimensions: the perception layer, the network layer, and the application service layer. Subsequently, it proposes corresponding multi-level security protection system design strategies and verifies the security protection effect of this system through actual experiments, with the aim of providing references for industry colleagues.