Abstract: Queqiao-2 relay satellite’s TT&C system can act as a relay node to enable the ground station to perform orbit determination of the lunar probe. Under the existing T&C system and the Earth-Moon distance, it is difficult to improve the telemetry rate and measurement accuracy. Therefore, it is necessary to design and verify a new TT&C system under deep-space conditions. A unified S-band carrier system was adopted to perform routine TT&C tasks between the satellite and the ground station. A four-way measurement link（ground station-satellite-probe-satellite-ground station）was designed to enable real-time measurement of lunar probes that are not visible from the ground station. Additionally, a GMSK + PN TT&C transponder was configured for application verification. Simulation results of the four-way lunar measurement demonstrate that it can achieve meter-level positioning accuracy for the lander. Estimations of the new TT&C system indicate that it can achieve centimeter-level ranging accuracy at the Earth-Moon distance. The actual operational performance and simulation verification results demonstrates that the TT&C system design of the relay satellite meets the mission requirements and can provide references for the design of TT&C systems for future deep space exploration and lunar exploration missions.