Abstract: Considering the existing water ring vacuum pump unit in a thermal power unit condenser, a steam injection vacuum system was installed, and a set of control logic was designed for this system. Based on the characteristics of the steam injection vacuum system, the control requirements and the logic design schemes of the system control strategy were researched and determined, while the method of using the sequential step program to configure the key process logic was proposed. After which, the application of the system logic design was verified. Verification results show that after the retrofit of the vacuum system, the annual average vacuum of the condenser is improved when the steam injection vacuum system is put into operation, which can reduce the heat consumption rate and improve the economy during unit operation, while the reliability of the unit operation can be improved with the addition of the available equipment in the vacuum system. This may serve as a reference for the engineering application of similar control strategies.