In this study, two filterless frequency-tupling millimeter-wave (mm-wave) generator schemes are theoretically analyzed and verified by simulation. The first one is a frequency 12-tupler, made by a dual-parallel Mach–Zehnder modulator (DP-MZM), capable of generating the six-order optical harmonic, directly. The second one is a frequency 36-tupler, consisted by the proposed frequency 12-tupler and an optical remodulator, which can utilize the six-order optical harmonic to generate frequency 36-tupling mm-wave signal and adjust the optical carrier to sideband ratio (OCSR) of the generated optical signal. The simulations show that without any filter, two frequency-tupling schemes both with good frequency tunability. By turning the RF driving signal from 5GHz to 8GHz, the frequency 12-tupler, with the frequency ranging from 60 to 96GHz can be obtained, and the optical sideband suppression ratio (OSSR) and the electrical spurious suppression ratio (ESSR) is over 37dB and 36dB, respectively. With the RF driving signal varying from 1.75GHz to 3.25GHz, a wideband mm-wave signals with the frequency ranging from 63GHz to 117GHz will generated by the frequency 36-tupler, the OSSR and ESSR is over 28dB and 23dB, respectively. Moreover, with careful adjusting the gain of remodulator, the OCSR of the mm-wave signal generated by the frequency 36-tupler can be continuous turning from 4.1dB to 44.1dB and the transmission performance of the proposed schemes based radio-over-fiber downlink system is also demonstrated.