Abstract: In gasdynamics and chemical lasers, the supersonic diffuser plays an important role in the pressure recovery system. This paper introduces some experimental and numerical results of an experimental supersonic diffuser under the normal temperature condition. Several factors affecting the diffusing performance are comparatively analyzed, including different divergent angles, with and without endwall energizers, horizontal vanes and vertical vanes. Preliminary study shows that the supersonic diffuser efficiency can be greatly improved by means of setting small divergent angle utilized into cavity of the laser and diffuser of the pressure recovery system, using vertical vanes with proper thickness set along the direction of inner width of the diffuser and endwall energizers on the left and rig