In order to increase the modulation bandwidth of frequency-modulated continuous wave (FMCW) light detection and ranging （LiDAR) for the high range resolution, with the use of external modulation mode based on dual-parallel Mach-Zehnder modulator (DPMZM), combined with the microwave photonic frequency multiplication technology where no optical filters were used, the broadband radio frequency(RF) modulated signal of 8 GHz was realized from a 1 GHz RF source. Furthermore, the effect of the variation of three parameters in the subsystem, namely extinction ratio, modulation index, and phase shift of phase shifter, on the performance of the built FMCW LiDAR system model was investigated. The results show that the extinction ratio of most commercial modulators can meet the requirements of use. When the modulation index is in the range of 2.385~2.425 or the electrical phase shifter error is not greater than 1.3°, the suppressed ratio of FMCW LiDAR detection signal peak power can be maintained above 20 dB. These researches provide theoretical support for the application of microwave photonic frequency multiplication technique in FMCW LiDAR and have certain reference significance for engineering implementation.