The current paper mainly focuses on finding a more appropriate way to enhance the fan performance at off-design conditions. The centrifugal fan (CF) based on flap-Adjustment (FA) has been investigated through theoretical, experimental, and finite element methods. To obtain a more predominant performance of CF from the different adjustments, we carried out a comparative analysis on FA and leading-Adjustment (LA) in aerodynamic performances, which included the adjusted angle of blades, total pressure, efficiency, system-efficiency, adjustment-efficiency, and energy-saving rate. The contribution of this paper is the integrated performance curve of the CF. Finally, the results showed that the effects of FA and LA on economic performance and energy savings of the fan varied with the blade angles. Furthermore, FA was feasible, which is more sensitive than LA. Moreover, the CF with FA offered a more extended flow-range of high economic characteristic in comparison with LA. Finally, when the operation flow-range extends, energy-saving rate of the fan with FA would have improvement. © 2018 by the authors.