The invention provides a source number estimation method of mechanical oscillation signals. The method comprises that a single-channel sensor collects the mechanical oscillation signals of a measured object whose background source number is uncertain; a wavelet packet decomposition method is used to carry out wavelet packet decomposition on the mechanical oscillation signals of the measured object, decomposing sub signals are obtained, and the decomposing sub signals and the mechanical oscillation signals form virtual multi-channel signals; a singular value decomposition method is used to decompose a virtual multi-channel signal matrix and further to obtain singular values of the virtual multi-channel signal matrix; a clustering method is used to carry out clustering analysis on the singular values of the virtual multi-channel signal matrix, and a clustering result of the singular values of the virtual multi-channel signal matrix is obtained; and the number of singular values in a cluster to which the maximal singular value in the clustering result belongs represents an estimated value of the background vibration source number. According to the invention, signals of a single measuring point are analyzed, the measuring point is clear, and benefit is provided for subsequent analysis.