Ac inductance parameter measurement is very important to the performance of the three-phase active compensator, A great influence on the accuracy of the active compensation inductance parameters.In this paper a new type of three-phase active power filter (APF) two arms inductance on the ac design Because the three-phase active compensator in the third phase and the other two arms two phase cable sex cannot directly using three phase three arms, the calculating method for parameters of the compensator.According to meet the requirements of rapid current tracking method and suppress harmonic current requirements, improve the upper and lower limits of inductance.And through the example, and comparing with other methods.The results show that the desires of the rationality of the formula.