A side face pumping slab waveguide DPAL laser device comprises an LD pumping module L, an LD pumping module R, a light guide pipe L, a light guide pipe R and a one-dimensional waveguide resonance cavity. The LD pumping module L and the LD pumping module R are symmetrically placed about the one-dimensional waveguide resonance cavity. The light guide pipe L and the light guide pipe R are symmetrically placed about the one-dimensional waveguide resonance cavity. All semiconductor laser devices of the LD pumping module L are placed on a spherical face in a stack array or linear array mode and point to a pumping window, wherein the pumping window, in the direction of the LD pumping module L, of the one-dimensional waveguide cavity serves as the center of the spherical face. All semiconductor laser devices of the LD pumping module R are placed on a spherical face in a stack array or linear array mode and point to a pumping window, wherein the pumping window, in the direction of the LD pumping module R, of the one-dimensional waveguide cavity serves as the center of the spherical face. the double-edge side face pumping mode is adopted for the laser device, and therefore the possibility that carbon-particle-polluted lasers generated after high-power-density pumping light and alkane type mixed gas react are output out of window pieces is greatly lowered; the light beam shaping process is simplified, and the problem that pumping light is not uniformly distributed is avoided; the modularized thought is adopted, and the laser device is suitable for various optical pump gas laser devices.