Aiming at the urgent needs of electronic information system for large broadband, parallel processing, flexible control, etc, this paper proposed a generation method of broadband optical frequency comb (OFC) with multi-combs, high flatness, and easy-tuning. By cascading a dual-parallel Mach-Zehnder modulator (DPMZM) and a dual-driven Mach-Zehnder modulator (DDMZM), and simply adjusting the direct current bias voltage and amplitude of radio frequency (RF) driven signal of two modulators, a frequency equally spaced OFC with 35 comb lines, flatness of 0.5 dB, and spurious signal rejection ratio of 15 dB is realized. In addition, the OFC generated by this scheme is easily tuned. By changing the frequency of RF driven signal, OFCs with different frequency intervals can be realized, and exhibite good stability.