At present, the performance of the traditional centralized coil antenna used for RFID detection and localization of underground cables is insufficient, which seriously restricts the improvement of its detection and localization distance. In this paper, a a new type of high field strength distributed RFID coil antenna structure is proposed. Based on the derivation of antenna related electrical parameters, the magnetic field strength of the coil antenna is taken as the objective function, and its quality factor is fixed as the constraint condition. Particle swarm optimization algorithm is employed to optimize the number of turns of the coil antenna and the turn spacing between adjacent two turns. Finally, an experimental test platform is built. The test results show that, compared with the traditional centralized RFID coil antenna, the distributed RFID coil antenna increases the reading distance by 33.3%, significantly enhances the received signal strength indicator (RSSI) at the same distance, and helps to improve the accuracy of the underground RFID localization method based on RSSI, which provides an important reference for the application of RFID detection and localization of underground cables.