Abstract: A real time PLL-less detection method for single phase random harmonic current was proposed. In the method,harmonic current is transformed to low frequency signals by a transform matrix instead of a phase lock loop (PLL) used in traditional harmonic current detection method,and the low frequency signals are extracted with the integral mean value method instead of low pass filter (LPF),tarmonic current is obtained through inverse transformation of the low frequency signals,he errors of the proposed method were analyzed. Simulation shows that the proposed method is not affected by DC bias,can reflect system frequency shift,and has better performances in terms of dynamic response and accuracy than the one that uses an LPF to extract low frequency signals.