Based on the observation data from an artificial precipitation enhancement field experiment, which was carried out on 21 August 2020 in the Qilian Mountains, the characteristics of the raindrop spectrum on the northern slope of the Qilian Mountains and the changes of raindrop spectrum characteristic parameters and spectrum types before and after the precipitation enhancement operation are analyzed. The results show that the precipitation was uneven, but the microphysical parameter eigenvalues of the three observation stations on the northern slope were relatively close. The average raindrop spectral widths were small, and the spectral patterns were basically the same, all of which were unimodal. The peak appeared at about 0.5 mm. The Gamma distribution had a good fitting effect on the raindrop spectrum. The distribution curve can more accurately reflect the distribution of the actual raindrop spectrum, but the fitting value in the peak section (0.5 mm) was biased, and the fitting result was slightly smaller than the measured spectrum. The 〖WTBX〗ZI〖WTBZ〗 relation satisfied the logarithmic correlation; the goodnessoffit 〖WTBX〗R〖WTBZ〗2 was above 0.86; and there was a good fitting relationship. After the operation, the raindrop size, total concentration, rain intensity, etc. all show an increasing trend. After the precipitation enhancement operation, the spectrum width of the raindrop spectrum gradually increased. The peak shape changed from single peak to double peak 10 minutes after the operation. The spectrum width continued to increase 30 minutes and 60 minutes after operation, indicating that the collision process between small raindrops in the cloud began to occur at this time, resulting in largerscale raindrops.