Based on a typical stratiform cloud precipitation weather process in the Northwest Sichuan Basin from 16 to 17 March 2018, the conditions and physical responses of artificial precipitation enhancement operations are analyzed by using the cloud model results, satellite images, radar echoes, and sounding data. Meanwhile, based on the observation data of raindrop spectra, the microphysical characteristic response analysis of artificial precipitation enhancement operations is carried out, and the distribution characteristics of particle size velocity spectra are mainly studied. The results show that: after the rainfall enhancement operations, the number of particles with different particle diameters and different particle speeds changed significantly; large particles increased obviously; the raindrop spectra widened; and the 0.437-1.625 mm diameter spectrum and 1.5-5.2 m/s speed spectrum became significantly wider. Meanwhile, there was no obvious jump in particle size and particle velocity. The interval value distribution relatively concentrated in the particle size of 0.312 to 2.125 mm with the particle velocity of 1.1 to 6.8 m/s. The artificial precipitation has a limited influence on the size and velocity of precipitation particles. During the influence period of artificial rain enhancement operations, the intensity of precipitation, rain water content, total number concentration and effective particle size remained consistent with their respective peaks, valleys, and oscillations, as that of the natural precipitation period. Artificial precipitation does not change the correlation between the physical quantities.