Using the cascade structure of an Electro-absorption Modulator (EAM) and a frequency modulator (FM), we proposed a new Optical Frequency Comb (OFC) generation scheme. The program structure is simple, easy to be controlled and the output noise is low. We conducted a theoretical analysis on the principle scheme and did research on the simulation with software of Optisystem7.0. The simulation results show that: we generated a flat optical frequency comb, whose center wavelength and line spacing can be tuned independently. Also，the effective bandwidth of the OFC is 3.8 nm, its line spacing is 5 GHz and number of lines is 105.