As power electronic devices become increasingly prevalent in modern power systems, harmonic pollution has become increasingly severe, with a growing number of harmonic sources. In this context, devices such as three-phase four-leg active power filters (APF) have demonstrated significant value in mitigating harmonics and enhancing power quality. Based on the analysis of the mathematical model of three-phase four-leg APF, this paper presents an integrated control scheme combining fractional-order sliding mode control (FOSMC) and fuzzy-hysteretic control (FHC). Specifically, the scheme adopts FOSMC to enhance the current tracking accuracy of APF, and employs FHC for the n-phase compensation current to suppress the zero-sequence component. A comprehensive control scheme is further developed to achieve coordinated control between the abc phases and the n phase. Simulation results from MATLAB/Simulink and experimental findings indicate that the proposed strategy effectively suppress the total harmonic distortion in the three-phase grid with relevant strategies. Moreover, the zero-sequence current is effectively suppressed, demonstrating excellent performance and strong potential for engineering applications.