Photonic generation of millimeter-wave (mm-wave) is very attractive for applications in radio-over-fiber for wireless communications,imaging,and r adio astronomy observations.A novel method based on dual-parallel Mach-Zehnder modulator (DPMZM) and four-wave-mixing (FWM) i n highly-nonlinear fiber (HNLF) is proposed for photonic generation of millimeter-wave signal with 24-t upled frequency.Firstly,the optical carrier and the ±2order optical side-bands are suppressed,while the ±4order optical side-bands are obtained by properly controlling the DC bias,modulation index of the DPMZM,a nd the phase shift of the phase shifter.Secondly,the ±4order optical side-bands are then injected int o the HNLF after erbium doped fiber amplifier (EDFA).The ±12order optical side-bands are generated due to FWM effect.After beating detecti on,a millimeter-wave signal with 24-tupled frequency is finally obtained.This proposed scheme is verified by si mulation.The technique has advantages of high frequency multiplication fact and high spectral purity.