To solve the problem of information being intercepted by illegal users during wireless communication, a secure transmission strategy based on optimal relay selection was proposed. Firstly, the pre-designed artificial noise and useful information were integrated at the source node, and the best relay selection algorithm was used to select the best relay to forward the received information. Secondly, the secrecy capacity, outage probability and interpret probability of the system were derived. Finally, the optimal number of relays were determined by the comprehensive performance of security and reliability. Theoretical analysis and experimental simulation results show that compared with the traditional system model without artificial noise, the performance of the proposed system can be significantly improved by adding relay nodes.