Abstract: Based on the data obtained in two flight detection tests in central Inner Mongolia in July 2020,the microphysical characteristics of stratiform clouds were analyzed,and the relationship between aerosol,CCN and cloud droplets was discussed in this paper.The results showed that the number concentration of precipitation particles and large cloud droplets was less than 100 cm^-3,while the concentration of small cloud droplets was much higher than that of large cloud droplets and precipitation particles,reaching up to 10³ cm^-3.The average effective diameter of small cloud droplets,large cloud droplets,and precipitation particles were 16.89 μm,241.92 μm and 655.27 μm,respectively.The particle number concentration of small cloud droplets increased first and then decreased with the particle size,which was a multimodal distribution.The particle number concentration of large cloud droplets and precipitation particles decreased with the increase of particle size.The liquid water content in the cloud was mainly concentrated below 1 g·m^-3,with an average value of 0.18-0.22 g·m^-3.There was a linear relationship between CCN ratio and aerosol effective diameter,and aerosols with larger particle size was more likely to be activated into CCN.There was a good positive correlation between aerosol concentration and CCN concentration under cloud and cloud droplet concentration within cloud.The more aerosol and CCN under cloud,the easier it was to be activated into cloud droplet.At low LWC,cloud droplet effective diameter was positively correlated with aerosol number concentration,while at high LWC,cloud droplet effective diameter was negatively correlated with aerosol number concentration.