The invention relates to a method for determining an inductance value at an alternating side of a shunt active power filter, comprising the steps of: (1) analyzing APF (Active Power Filter) piecewise linearity switching characteristics caused by the switching and the breakage of a main circuit power device, and establishing a discrete model; (2) iteratively calculating an arithmetic solution of the discrete model by using a time domain method, i.e., calculating an instantaneous value and a steady state value of APF compensating current; and (3) determining the relationship between an inductance value at the alternating side of the APF and the tracking index required for the engineering through the instantaneous value and the steady state value of the compensating current obtained through calculation; and when the index of the engineering is known, the precise and reasonable inductance numeric area at the alternating side is obtained through the relationship. In the invention, the strong nonlinearity of the APF and the practical engineering index are comprehensively taken into consideration, and the inductance numeric area obtained through design is more accurate. The APF is ensured to meet the design requirement, and the compensating precision of the APF is improved.