The utility model belongs to the technical field of shield tunneling machine construction. A relay pump station for shield tunneling machine hydraulic system deep well split launching comprises a valve set connected between a shield tunneling machine main machine and shield tunneling machine rear corollary equipment, and the valve set comprises a first port communicated with the shield tunneling machine rear corollary equipment and a second port communicated with the shield tunneling machine main machine. A metering pump is arranged between the oil tank and the first port, and the oil tank iscommunicated with the second port through an oil return pipeline; and the electric control assembly controls the action of the metering pump according to the liquid level of the oil tank. The hydraulic system can be assisted, when the pressure of the main driving motor is too large, leaked oil generated by the main driving motor flows into the oil tank through the second port, meanwhile, the liquid level of the oil tank is automatically controlled, the stability of the whole system is met, and therefore smooth proceeding of whole split starting operation is achieved.