The relationship between stimulated Raman scattering characteristics and the polarization direction of a pump light was researched by taking an a-cut SrWO4 crystal which belongs to the tetragonal crystal system as a research object. Using a 532 nm light as the pump source and a single passing way as implementation, the anisotropy for the SRS’ gain of a-cut SrWO4 crystal was determined. The experimental results on the strongest Raman frequency shifting of 924 cm-1 come from the symmetrical stretching vibration of ［WO4］2-tetrahedron show that the gain coefficients appear two maximum values of 10.1 cm/GW and 14.2 cm/GW respectively when the pump light is polarized on a and c axes, and the gain coefficients present two of the same minimal values of 7.1 cm/GW when the pump light is polarized along the bisector of a and c axes. The results are interpreted using a Raman tensor and the nonpolar Raman scattering intensity theory, which demonstrates that experimental results in this paper are in good agreement with that of the theory.