In this study, a new device for the internal excitation test of soft soil was designed, and an instantaneous optical measurement system for the internal excitation response of soft soil based on digital image correlation(DIC)technology was developed. The relationship between the soil amplitude and the distance from the source, vibration frequency and confining pressure was studied. The results show that the soil amplitude decreases with the increasing distance from the source, and the amplitude attenuation curve is fitted in the form of power function. The affected range and degree of internal excitation can be visually and accurately represented by the affected zone of internal excitation based on DIC technology. The affected zone increases with the increasing vibration frequency, and significantly decreases with the increase of confining pressure.