Abstract: In order to study effect of Compton scattering on the modulation instability in the un-magnetized plasma,the modulation instability of the un-magnetized plasma under Compton scattering was analyzed and simulated based on the model of the multi-photon nonlinear Compton scattering.Some important data about effect of Compton scattering on the time rise rate of the modulation instability,the nonlinear dispersion and control were obtained,and a new mechanism of the modulation instability formed by the incident light and the Compton scattering was put forward.The result shows that the maximum time rise rate of the modulation instability and laser self-focusing in the un-magnetized laser-plasma becomes smaller than before the Compton scattering,and the time rise rate of the modulation instability in the vicinity of the laser-plasma surface is increased.