Abstract: In view of the problem of collinearity of harmonic emission level evaluating method of coal mine power system based on multivariate linear regression, which leaded to the problem that evaluation result was greatly affected by abnormal value problem, ridge regression method was proposed to estimate user side harmonic emission level and to divide responsibility of harmonic source. The principle of ridge regression estimation method was analyzed, and system side and user side equivalent circuits were established. Regression equation was established according to the equivalent circuit, and the regression coefficient was obtained by the ridge regression operation, and then user side harmonic emission level was obtained according to the ridge regression calculation result. The simulation results show that compared with the binary linear regression, the ridge regression estimation method can solve the collinearity problem more effectively, make accuracy of regression coefficient higher, thus obtaining more accurate harmonic emission level.