The invention relates to the technical field of laser processing, and particularly relates to a wafer grooving method and device. The wafer grooving method comprises the steps that the laser beam is divided to obtain the first beam and the second beam, the first beam and the second beam are focused on a metal layer on the back face of a wafer, the first beam and the second beam conduct cutting along the same straight line so as to remove the metal layer corresponding to a cutting path, and a groove is formed in the back face of the wafer. By means of the wafer processing method, grooving processing is conducted on the back face of the wafer, the metal layer corresponding to the cutting path on the front face of the wafer is completely removed, in this way, the dimorphism cannot appear during hidden cutting processing and mechanical cracking of the front face of the wafer in the follow-up process, the sheet diving yield and efficiency of the wafer is improved accordingly, and the waferprocessing device comprises a laser, a spectral assembly, a focusing element, a first reflecting mirror set and a processing platform.