The invention provides a method and a system for finding a direction of a target source of an array signal. The method comprises the following steps: performing signal sampling on the array signal to be detected to obtain a sampling matrix of the array signal, and acquiring a preset base matrix and a regularization parameter; performing singular value decomposition on the sampling matrix to obtain observation data, transferring the observation data into a signal subspace to obtain a target matrix; determining a target source direction of the array signal according to the target matrix, the base matrix, the regularization parameter and a preset direction finding equation set. According to the scheme, the target source direction finding of a high-dimensional signal can be abstracted into solution of underdetermined system of equations, so that effects of lower reconstruction error and higher success rate can be achieved within a larger signal-to-noise ratio range, and signals with higher correlation can be identified.