The invention discloses a noise prediction method for a power line communication system, which performs prediction on communication noise by taking an improved higher-order Markov model as a basis. The method comprises the following steps: acquiring communication noise data; performing discretization processing on the acquired noise data to obtain a discrete random sequence; using an improved higher-order HM-gMTD model to perform analysis prediction on the discrete noise random sequence; and utilizing an EM algorithm to perform parameter estimation on the above model. According to the invention, the recessive process of the HM-gMTD model is popularized to a higher-order Markov chain from a first-order Markov chain, and the EM algorithm is utilized for parameter estimation so that the accuracy of communication noise prediction is improved.