A full-field deformation measurement method using moire fringes generated at high scanning speed under a laser scanning microscope (LSM) was proposed. The formation principle and the deformation measurement principle were presented. Simulation and experiment verifications were performed to show the effectiveness and the accuracy of the proposed fast scanning moire method, where the scanning line spacing is an integral multiple of the basic scanning line spacing. The moire spacing, and the deformation measurement sensitivity and accuracy are almost the same as in the traditional LSM scanning moire method. The fast scanning process allows a high scanning speed and a large view field without reducing the deformation measurement sensitivity. The higher measurement speed makes this method more suitable to be combined with the phase-shifting technique than the traditional LSM scanning moire method. Besides, the application scope of the LSM moire method in the field of deformation measurement is extended because more specimen gratings can be used to generate moire fringes.