In recent years, the deployment scope and coverage of Roadside Units (RSUs) have been continuously expanding, and their impact on vehicular network communication has also been steadily increasing. The rising deployment rate of RSUs inevitably leads to increased energy consumption of infrastructure. From the perspectives of device lifespan and network security, studying reasonable sleep strategies to reduce RSU energy consumption and extend device longevity can indirectly enhance network security. This paper proposes a vehicular network transmission protocol based on RSUs sleep. Under the premise of ensuring the timeliness of cached data at vehicle nodes, the RSUs determine whether to enter sleep mode and the depth of sleep in the next time slot based on the length of the requested caching queue. Simulation results show that the proposed protocol effectively reducing the energy consumption of RSUs.