The invention discloses a separation method for in-band-on-channel digital-analog audio broadcasting signals. The method concretely comprises the first step that frequency modulation mixed signals are received; the second step that initial estimations of analog signals and digital signals are obtained; the third step that the analog signal estimations and the digital signal estimations are updated, the analog signals subjected to frequency modulation within a time domain have constant envelope characteristics, new analog signal estimations are obtained, and then the digital signal estimations are updated; the fourth step that different analog signal estimations and digital signal estimations are combined to obtain five candidate pairs, and the candidate pair with the minimum noise energy is selected; the fifth step that the third step and the fourth step are repeated to form an iterative loop, and iterative separation is performed on the analog signals and the digital signals. According to the separation method, different separation technologies and signal characteristics are fully combined, the performance of recovered digital signals is better, the digital signals recovered from a receive party are closer to corresponding sent digital signals, and the mean square error is improved by 2-5 dB.