Abstract: The advent of the 5G era has accelerated the development of IoV technologies with vehicle-road collaboration at the core.Efficient, reliable, and secure communication quality will be the basic requirements for implementing an intelligent traffic management system and improving smart travel.Therefore, for the scenario of relay cooperative transmission of IoV where information stealers exist, an opportunistic relay selection strategy and maximum ratio combining technology are used to design a secure transmission scheme in which the direct transmission link and the multi-hop relay forwarding link coexist, aiming to improve the reliability and security of information transmission.At the same time, based on obtaining the channel probability density function and cumulative distribution function, a closed expression for the secure outage probability of the IoV system based on DF(Decode-Forward) relay cooperative transmission is derived using methods such as the full probability formula.The information transmission channels involved are all subject to the Nakagami-m distribution, which makes the theoretical derivation more difficult. The final simulation experiments confirmed the accuracy of the theoretical derivation and the feasibility of the scheme.