Abstract: Addressing the issue of obstructed transmission of monitoring data during the construction and operation of long and large tunnels (groups), a data transmission method is proposed based on LoRa and the data relay technology. By analyzing the communication distance, anti-interference capability, and low-power characteristics in the special environment of tunnels, a data transmission communication network scheme for long and large tunnels (groups) was designed. Corresponding wireless relay and wireless gateway devices were developed, enabling reliable data transmission between remote servers and on-site tunnel sensors. Experimental and testing results show that the proposed LoRa-based data transmission technology for long and large tunnels (groups) can achieve interconnection between remote servers and on-site sensors, meeting the requirements for long-distance communication and low-power operation during the construction and operation of long and large tunnels.