Shunt Active Power Filter (APF) is one of most preferred filters for the mitigation of harmonics in power systems. The controller part of shunt APF plays an important role to generate a reference current which compensate/cancel the distorted currents. The APF injects current equal but opposite to the harmonic components, in turn the fundamental components only flows in the point of common coupling (PCC). In this studying, for four controls algorithm are proposed to control the shunt active filter. Instantaneous Active-Reactive Power Theory (PQ), an adaptive phase locked loop (PLL), Instantaneous active and reactive current method (DQ) and Synchronous detection method (SD) are designed to generate the reference current of APF for mitigation of harmonics. The performance of the four methods are analyzed and compared under different operating conditions. The load is assumed to have high nonlinear characteristics. Digital simulations are carried out to demonstrate the performance of the proposed algorithms using matlab/Simulink software package.