Abstract: Using 6328nm red light,we have made the experimental studies to two wave light coupling in Ce:KNSBN single crystal and demonstrate that the gain coefficientΓof two-wave coupling is a function of the crossing angle 2θ of two beams.According to fitting of Γ-2θ experimental data,the effective photo refractive charge density,the effective electro optical coefficient and the hole electron competition factor have been derived.These results are useful to optical information processing.