The present invention discloses a method for modeling background noise in a low-voltage power line channel, comprising the steps of: A. simulating colored background noise and narrow-band noise using MATLAB software, to obtain time-domain simulation diagrams of the two noise, and calculating spectrum and power spectrum density thereof; B. modeling for the simulated noise using a peak-type Markov chain; C. performing n-layer wavelet packet decomposition on simulated noise signals using wavelet packet transform; D. performing peak-type Markov chain modeling on 2n wavelet packet coefficients; E. counting by the peak-type Markov chain to obtain a state transition matrix with increased amplitude and a state transition matrix with decreased amplitude, and constructing new wavelet packet coefficients; F. reconstituting one-dimensional noise signals layer by layer, to obtain a new noise sequence; and G. verifying whether the simulated noise data is coincident with the modeled data using a rootmean square error.