The development of automation technology in power generation systems has become an urgent necessity to enhance operational efficiency and reliability. This study aims to design a control system using a Programmable Logic Controller (PLC) to monitor auxiliary equipment at the Golang Hydropower Plant (PLTA Golang). An effective monitoring system is essential to ensure the optimal operation of auxiliary equipment, such as cooling pumps, lubrication systems, and control valves. The research methodology includes system requirements analysis, PLC control circuit design, ladder logic programming, and testing on a prototype that simulates operational conditions in the field. The results of system implementation show that using a PLC can improve monitoring efficiency by providing real-time data on the condition of auxiliary equipment. The system is also equipped with a (HMI), which facilitates supervision and decision-making for operators. Based on the testing results, the system successfully detected faults and provided automatic alarms, reducing the potential for equipment damage and improving the reliability of the power plant system. In conclusion, this PLC design offers an effective solution that can be implemented to support the operation of PLTA Golang more efficiently and reliably.