In order to acquire uniform and flatten Gaussian beam, a new resonator is designed. The beam intensity distribution is modified to obtain greater temporal uniformity by reflector′s periodically vibrating. The theoretical model of this beam shaping was built and analyze. Simulated and experimental results are presented that the high-power CO2 laser beam intensity distribution uniformization can be achieved using the new resonator. The novel method avoided some shortcoming in high power CO2 laser beam shaping and simplified the whole system.