Based on the S-band dual polarization radar data in Yingkou， the microphysical characteristics of the polarimetric process of the rare heavy snow in Liaoning Province from November 7 to 8， 2021 were analyzed. From the analysis of the radar vertical profile of the heavy snowfall center， it is concluded that the echo above 15 dBZ extends to about 8 km during the heavy snowfall period （17：00—20：00 on November 7， UT）， and the horizontal reflectivity factor Z_H of 35 dBZ extends to over 5 km. In addition， the lower layer below 3 km was dotted with strong reflectivity factors above 40 dBZ， which indicates that the snowfall process was characterized by strong convection， and the deeper the moisture condition in the air， the easier it was to form large-diameter snowflakes and produce strong snowfall. However， the differential reflectance （Z_DR） ranges from -0.3 to 0.3 dB， with Z_DR values close to 0 in both the upper and lower layers. The shape of the falling particles was approximately spherical， indicating that the particles of snow in the air was mainly spherical ice crystals and snowflakes in the air. K_DP appears abnormal large value， the height reaches 7 km， which indicates that the concentration of snowflakes increases obviously， and can be used to predict the jump of snowfall intensity. The microphysical characteristics of heavy snowfall particle radar in the middle of Liaoning Province were as follows： The maximum and the average of Z_H were 33~35 dBZ and 21~26 dBZ respectively in the estimation of heavy snowfall≥2 mm， and the average value and the maximum value of Z_DR were -0.3~-0.2 dB and 0.3~0.8 dB， which indicated that the snowflakes section fell more vertically under the influence of updraft during the heavy snowfall， while the snowflakes section was more horizontal during the weak snowfall. The maximum and average values of K_DP are 0.2~0.4 （°）·km^-1 and 0.1~0.2 （°）·km^-1 respectively， which indicates that the concentration of snowflakes was higher and CC is higher than 0.98 during heavy snowfall， but the consistency of the particles was good， basically for dry snow. At the same time， the Z_DR polarization parameter can better identify the phase characteristics of dry snow， and ML and HCL products have good practical value in determining precipitation particles.