Abstract: The sodium laser guide star (LGS) technique which adopted range gating and common aperture mode was researched, and the projecting-detecting experiment was studied. The relationship between sodium resonance scattering and wavelength of beacon laser was analyzed. The development of sodium beacon laser, range gating device, the set of back-scattering detector, synchronous control device etc, was introduced. Sodium beacon images were collected successfully in the experiment. The law of back-scattering images’ varying according to wavelength of laser was analyzed, wavelength matching was proved to be important in sodium LGS．