This paper discusses in detail an intelligent inspection system of sewage treatment plant based on Augmented Reality to solve the problems of low efficiency, slow speed and waste of human resources in the existing daily inspection process of wastewater treatment plant. The intelligent inspection system designed in this paper is realized based on Augmented Reality technology, and a Digital Twin model is built to connect with the running data of the wastewater treatment plant in real time. Hololens2 headset is used to realize human-computer interaction. The intelligent inspection system is connected to multiple sensors in the wastewater treatment plant through PLC, and the real-time data in the scene is dynamically presented in the model. Through the sensor of Hololens2, the system can quickly identify the current position of the inspectors, map the model and real-time data of the corresponding scene into the reality, and mark the data with problems, so as to help the inspectors quickly judge and deal with the problems in the operation of the wastewater treatment plant. The structure and implementation of the system are introduced in detail in this paper.