Abstract: Using the model of the nonlinear Compton scattering of an electron and multi-photon group and the non-paraxial propagation equation,the small-scale self-focusing of the non-paraxial laser beams under the multi-photon nonlinear Compton scattering was studied,and the influence on the small-scale self-focusing taken place by the coupling optical formed by incident and scattered optical beams was discussed.An analytic expression for the gain spectrum was obtained.The results show that the influence on the small...