The invention relates to a medium-short-wave radio broadcast signal detection method which is suitable for a power line carrier communication system in medium-low-voltage power distribution network environment. The power line carrier communication system comprises power line carrier communication equipment and a power line channel. The method includes that the power line carrier communication equipment collects noise of the power line channel by means of differential-mode coupling, time-frequency domain analysis is performed through short-time Fourier transformation, an average value of noise strength of each frequency point within sampling time is calculated, and whether medium-short-wave radio broadcast signals enter or not is detected finally on the basis of a judgment threshold. The medium-short-wave radio broadcast signal detection method is suitable for medium-short-wave radio broadcast signal detection of power line carrier communication systems of medium-low-voltage power distribution networks within a frequency range of 500kHz-30MHz.