A new method is proposed to generate microwave and millimeter-wave by using polarization scrambler and polarization maintaining fiber (PMF), which is based on the coupling and the interaction between the two polarizations of the initial non-chirp Gaussian optical pulse in PMF. The expressions of the microwave and millimeter-wave are derived by couplemode theory. Moreover, the feasibility is analyzed simulatedly. At last, 0−120 GHz microwave and millimeter-wave can be produced by adjusting system parameter or input pulse duration. The project is of great simplicity, stability and high export efficiency. This work has been jointly supported by the National Natural Science Foundation of China (60771008), Program for New Century Excellent Talents in University (NCET-06-0076), Beijing Natural Science Foundation (4082024), the Ph.D. Programs Foundation of Ministry of Education of China (200800040002), the Foundation for the Returning Scholars (2008890), and the Beijing Jiaotong University Foundation (2006XM003)