Programmed Logic Controller (PLC) is the digital calculation operation system, which is specially designed for industrial working environment. This paper proposed the implement of hydraulic control system for large-scale railway maintenance equipment based on PLC. This implement pursued the purpose of accurate control of hydraulic working units of large-scale railway maintenance equipment. Large-scale railway maintenance equipment should always work in efficient statement. Focusing on this requirement, the reliability design of hardware for current leakage and impulse current which is proposed in the paper is necessary. This paper proposed Triple Modular Redundancy (TMR) for relative horizontal check of working units linking bridge. This paper also proposed the method to prevent the current leakage and impulse current. As for hydraulic valves, this paper proposed PID algorithm to realize the control of Analogue Closed-Loop.