Abstract: The accurate evaluation of radar coverage is an important basis for ensuring the quality of the new generation of weather radar observation data, and the height of the melting layer is one of the most important factors that affect radar coverage. The terrain of Sichuan Basin and its surrounding area is complex, with various features of the underlying surface, and the height distribution of the melting layer is complex and changeable. Based on the sounding data of southwest vortex observation experiment, the characteristics of time and space distribution of the melting layer height was analyzed through statistical method, which lays the foundation for better application of radar data. The main results are as follows: The average height of the melting layers over the Sichuan Basin and its surrounding are all over 5000 meter, but the difference of the maximum and minimum height of the melting layers among 11 observations is very huge and the maximum deviation is up to 2353 meter. Mean square error values show that there are significant differences in Discrete degree of the height of the melting layer in 11 sites, especially in higher latitude sites. There is certain diurnal variation in the height of melting layer, and the transition zone of the plateau to the basin is the sensitive region of the characteristics. The height of the melting layer various in different weather conditions, and the height of melting layer in most sites usually rise with the increase of cloud total amount.