The detection performance of frequency modulated continuous wave (FMCW) and pulsed laser detection systems under aerosol interference were investigated, and the detection performance comparison between the two systems was proposed. Based on Monte Carlo method, the target detection model under aerosol interference was established. The detection results of different distance targets were studied. The feasibility of comparing the two systems of FMCW and pulse system was demonstrated, and the quantitative comparison of the detection performance of the two systems was carried out. Taking the phosphorus smoke aerosol as an example, the simulation and the distance measurement experiment in the fog chamber were carried out. The results show that the FMCW laser detection system can improve the detection performance by increasing the modulation frequency. In an aerosol environment, FMCW laser detection has a higher signal-to-clutter ratio (SCR) than the pulse system, which means better detection performance and stronger resistance to backscattering interference. Under the condition of low aerosol visibility and the same range resolution, the detection performance of the FMCW system with 400 MHz initial modulation frequency is about 8-10 dB higher than that of the pulse system.