The invention discloses a dual-optical-path three-dimensional speckle interference system based on spectroscopes. The system comprises a laser, a first spectroscope, a second spectroscope, a third spectroscope, a fourth spectroscope, a fifth spectroscope, a first totally-reflecting mirror, a second totally-reflecting mirror, a third totally-reflecting mirror, a fourth totally-reflecting mirror, a first beam expanding mirror, a second beam expanding mirror, an amplification system and a CCD camera. The advantages are that transient three-dimensional displacement in the laser processing process can be given, and time and space resolution capability can be improved with further development of a high-speed photography system and a long-distance microscope; and electronic speckle interferometry and digital speckle correlation are combined organically and respective advantages thereof are utilized, thereby facilitating measurement and providing effective and practical experimental means for micro-scale transient three-dimensional thermal deformation needed in the study of laser processing.