Abstract: To study the factors that affect the operation efficiency of axial-flow fans in a thermal power unit, the energy consumption characteristics of the axial-flow fans were analyzed, while a comparison was carried out on the energy consumption between the operation mode of a single axial-flow fan and two axial-flow fans in parallel arrangement. Based on energy consumption analysis of the axial-flow fans, an optimal design scheme was proposed for the axial-flow fan. Results show that when the unit operates at low load, the independent operation mode with a single axial-flow fan could effectively reduce the energy loss and improve the fan efficiency, compared with the parallel operation mode with two axial-flow fans. For the thermal power unit, it is suggested adopting the operation mode with a single axial-flow fan under low load condition, and adopting the parallel operation mode with two axial-flow fans under medium and high load conditions, and between the two modes, automatic undisturbed switching could be realized through the introduction of command coefficients of the axial-flow fans.