The active power filter has been proved to be an effective method to mitigate harmonic currents generated by nonlinear loads as well as to compensate reactive power. The main objective of this work is to develop a new control strategy to improve the performances of shunt active power filter for mitigating current harmonics under balanced and unbalanced sinusoidal source voltage conditions. To achieve this objective a shunt active power filter (SAPF) is proposed with a sliding mode control (SMC) strategy for the DC bus capacitor voltage regulation and currents reference estimation. The analysis and simulation results using Matlab/Simulink are presented and discussed showing the effectiveness of the control algorithm and confirm performance improvement of fuzzy logic technique used for the source current control which provides flexibility, high precision and fast response.