A frequency-quadruple microwave signal method based on dual-parallel Mach-Zehnder modulator (DPMZM) was proposed. The frequency-quadruple principle was theoretically analyzed. The upper sub-MZM of the DPMZM was modulated by RF signal and operated at the maximum transmission point (MATP), while only an optical carrier was obtained from the bottom sub-MZM of the DPMZM. Then the DPMZM worked at the carrier-suppressed even-order sideband modulation mode. In order to improve the purity of quadruple frequency signal, optical bandpass filter(OBPF) was used to remove the high-order spurious sideband. Microwave photonic frequency-quadruple system was built based on DPMZM, and its performance was tested experimentally. The results demonstrate that the optical sideband suppression ratio (OSSR) and radio frequency spurious suppression ratio(RFSSR) can reach 21.09 dB and 28.41 dB, respectively. Since no extra electronic devices were used, the system can generate radio frequency with frequency up to 80 GHz. DPMZM based microwave photonic frequency-quadruple system had the advantages of simple structure, convenient operation and good frequency-quadruple performance, which can realize high purity and high frequency quadruple frequency generation.