The invention discloses a laser capable of realizing sub-nanosecond Q-switched output by controlling the characteristics of pump light, and belongs to the technical field of all solid-state lasers. It includes a pump source arranged in sequence along the propagation direction of the light, a fiber coupling device, a rear cavity mirror, a laser gain medium, an electro-optic Q-switching element, and a coupling output mirror, in which the rear cavity mirror, the laser gain medium, the electro-optic Q-switching element and The outcoupling mirror forms a resonant cavity. The pumping source is a semiconductor laser, which outputs pumping light polarized in the π direction. The length of the resonant cavity is less than 30mm. The laser gain medium is Nd with linear polarization absorption characteristics: YVO Crystal, the output end face of the laser gain medium is cut along the a-axis to form a Brewster angle, and the pump end of the laser gain medium passes through the optical surface coating as Rear mirror. The laser has the advantages of simple and compact structure, easy modular production, high output pulse stability and the like.