This paper aims to propose a design scheme for a rail transit signal automation control system based on PLC technology， in order to enhance the transportation efficiency and service level of urban rail transit. By constructing a system architecture that includes three major modules: Data acquisition and monitoring， signal control and point management， and fault detection and emergency response， and combining it with practical application testing， the results show that the system exhibits excellent performance in aspects such as signal switching delay time， train positioning accuracy， and improvement rate of operational efficiency. The research confirms that this system not only enhances the safety of rail transit but also significantly improves operational efficiency.