Abstract: The channel broadcast characteristics of the full-duplex (FD) non-orthogonal multiple access (NOMA) cooperative vehicular communication network will lead to communication interruption or failure, which is difficult to effectively guarantee the security of the vehicular communicate. A NOMA-FD optimal relay selection scheme is proposed in order to reduce secrecy outage probability (SOP). In the scheme, any relay transmitted interference noise to eavesdropping vehicular users meanwhile the selected NOMA-FD relay used the residual self-interference elimination technology to jointly guarantee the safe and efficient data transmission of legitimate vehicular users. Numerical analysis verified our theoretical results. Note that secrecy outage probability of the system can be greatly reduced by reasonable parameter setting, and the security performance of the system can be improved effectively while ensuring lower complexity.