Abstract: In view of problems that traditional ip-iq harmonic current detection method can get fundamental frequency and initial phase angle of three-phase current by using PLL, but the method has low detection precision and complex circuit when power voltage occurs distortion, the paper proposed an improved method of harmonic current detection without PLL. It detailedly analyzed detection principle of the improved method under conditions of symmetric and asymmetric three-phase current when power voltage occured distortion, and gave implementation of the improved method applied in harmonic current detection of single-circuit. The experiment results show that the improved method can detect harmonic current accurately and real-timely and has simple algorithm.