The detection of harmonic sources on the point of common coupling (PCC) is the important premise of responsibility proration and harmonic elimination. In this paper,a method of nonlinear load detection based on harmonic distortion power is proposed, which is applicable for the IEEE Std. 1459-2010 standard. By comparing the corresponding relationship between the instantaneous power components and apparent power components of linear and nonlinear load cases, the effectiveness of the proposed method is proved. Multiple cases of simulation analysis and measurement results prove the validity and rationality of this method.