The reactive current detection methods in reactive power compensation device based on instantaneous reactive power theory were discussed in the paper. By analyzing the quality of various kinds of harmonious and reactive current detection methods in power system, and according to different compensation requirement, two reactive current detection methods ip-iq method and Hilbert method were adopted. Then it gives simulations on these two models to analyze their comprehensive performance of both stable state and dynamic state. Finally, gives a verification under a IC hardware platform.The result shows that these two methods can well inspected the three-phase reactive current, and then to complete the system compensation.