Under the influence of cloud and fog, pulsed laser fuze has the problems of high false alarm probability and poor ranging accuracy. These problems restrict the all-weather work of laser fuze. In order to reduce the influence of cloud and fog on the full-waveform sampling laser fuze, the paper proposes an echo pulse processing method based on Gaussian decomposition. The Gaussian model is used to decompose the echo signal into the form of individual Gaussian pulses, the real target echo and backscatter echoes of cloud and fog can be distinguished according to the waveform characteristics. The performance differences between the Gaussian decomposition method and the digital cross-correlation methods are compared from theoretical simulation and experiments. The results show that under the condition of cloud and fog with visibility less than 4 m, the ranging accuracy of the digital cross-correlation method deteriorates to 1.6 m, while the ranging accuracy of the Gaussian decomposition method can achieve a distance of 0.18 m, it is better than traditional cross-correlation process. It provides a new data processing idea for the high-precision ranging of laser fuze in cloudy and foggy environment.