The main project of the 5 # electrostatic precipitator maintenance is to replace the ID fan rotor. The construction period is from July 15th to 27th, 2017, with a total planned duration of 13 days. This project requires high technical accuracy and complex process procedures. During on-site construction, due to the influence of the factory structure on the top of the fan, protective measures need to be taken to remove it. In addition, it is necessary to measure and record the data of each installation part before dismantling the fan. After dismantling and reinstalling the new rotor, the installation and alignment should be carried out, and the installation accuracy of the coupling should be 0.05m. The maintenance project was completed on time and highly praised by the owner.