Non-intrusive load monitoring (NILM)as an important part of intelligent electricity technology system, has great research significance. In this paper, a two-layer classification method based on k-NN algorithm for non-intrusive load monitoring and disaggregating was proposed. The active power and reactive power were taken as the load characteristics identified in the first layer, and the 3,5 harmonics of the current were taken as the load characteristics identified in the second layer. Through the k-NN algorithm, the load to be disaggregated is compared with the data in the training set to realize the load identification finally.