In order to carry out the cloud-seeding operation scientifically and accurately, the King-air 350 aircraft (no.3523) equipped with airborne particle measurement systems (PMS) entered the cloud for vertical and horizontal detection, and combined with FY-2F satellite, weather radar and other data, the microphysical structure of a low trough cold front stratified cloud system in southern North China on February 28, 2021 and the rainfall enhancement operation conditions were comprehensively analyzed. The results show that the precipitation cloud system is a medium and low cloud. The cloud top height observed by the aircraft is 6 014 m, the cloud top temperature is -17.7 ℃, the cloud bottom height is less than 582 m, the 0 ℃ layer height in the cloud is 1 300 m, the cloud body thickness is more than 5 400 m, the warm cloud thickness is more than 700 m, and the cold cloud thickness is more than 4 700 m. The cloud top height retrieved by satellite ranged from 5 to 6 km, which is consistent with the aircraft measurement result. The cloud top temperature retrieved by satellite ranged from -40 to -25 ℃, which is lower than the aircraft measurement result. The microphysical structure of the cloud system during the whole detection period is nonuniform. In the cold cloud, the second layer of ice water mixing zone (height ranged from 3 427 to 4 985 m, temperature ranged from -12.4 to -6.3 ℃) and the third layer of ice water mixing zone (height ranged from 5 449 to 6 014 m, temperature ranged from -18.3 to -15.3 ℃) appear large particle number concentration areas detected by cloud drop probe (CDP), the maximum values are 146.80 cm^-3 and 170.75 cm^-3, and the supercooled water content reach 0.12 g·m^-3 and 0.20 g·m^-3, respectively. The microphysical distribution of warm clouds is relatively uniform. The particle number concentration fluctuates at a height of 557-575 m and 844-866 m. The particle number concentration detected by CDP varies relatively large, while the concentration of particles detected by cloud imaging probe (CIP) and by the high volumeprecipitation spectrometer (HVPS) vary relatively small.The microphysical distribution of clouds within cold clouds is not uniform. The number concentration fluctuations of cloud particle within the cold cloud region are significant at a height of 3 603-3 617 m, 5 445-5 542 m, and 5 705-5 847 m, with multiple jumps.The particle spectral widths detected by CIP and HVPS in warm cloud region are narrower than those in cold cloud region, and the cold cloud is mainly composed of solid ice particles. In the early spring, the mixed stratiform clouds are prone to appear in the early stages of precipitation systems of low trough cold front stratiform clouds, and there is a certain amount of supercooled water near the cloud top. It is suitable to identify the rain-increasing timing and the precipitation-increasing location for sowing cold cloud catalysts. Artificial seeding has great potential for catalysis.