The invention provides an acquisition method for an instantaneous frequency of a dynamic response signal of a high-speed train and a device thereof. The acquisition method comprises the steps of acquiring a time frequency plane which corresponds with the dynamic response signal of the high-speed train; extracting each discontinuous frequency curve in the time frequency plane; combining the discontinuous time frequency curves according to a preset rule, and obtaining an instantaneous frequency curve which corresponds with the dynamic response signal of the high-speed train; and determining theinstantaneous frequency of the dynamic response signal of the high-speed train according to the instantaneous frequency curve. The acquisition method and the device thereof can quickly and accuratelyacquire the instantaneous frequency of the dynamic response signal of the high-speed train.