In the field of artificial precipitation enhancement, aircraft observation is still the only effective ways to directly obtain the phase state of cloud particles. Because the liquid supercooled water content in the cloud is an important parameter to judge the microphysical structure characteristics of the cloud system, based on the layered vertical detection data of Par-ticle Measurement System (PMS) in the Sanjiangyuan National Nature Reserve, we analyzed the microphysical charac-teristics of a typical layered cloud system in this area in spring. The results show that: (1) the typical stratiform cloud system in spring cloud system is mainly composed of three layers, the uppermost Cs (cirrostratus) is ice-phase cloud, and the AS (altostratus) in upper layer (high-level cloud) and the lower layer are mixed clouds. Moreover, the high super-cooled water area is mainly distributed in the middle, upper and lower parts of the low-level As, where the cloud particle concentration and supercooled water content are the highest, with obvious regional characteristics. (2) The liquid cloud particles in the As layer are concentrated in the median diameter range of 3.5 ~ 27.5 μm, and the cloud particles larger than 30.5 μm are ice-phase. In the middle and upper part of the low As layer, there is an obvious growth phenomenon in the high supercooled water area, and there is obvious ice crystals effect in the middle and lower part. (3) In the low su-percooled water area, the average content ratio of supercooled water is 90.8±10.9%, and the middle to lower parts (95.6±5.6%) is significantly higher than the middle and upper parts (79.8±12.1%). The accurate understanding and judgment of the microphysical structure of the layered cloud system in Sanjiangyuan will provide a reliable observation basis for the catalysis of artificial precipitation enhancement in this area.