Aircraft icing accumulation is a serious threat to flight safety, and its formation is influenced and constrained by microphysical features and processes in clouds, so it is important to study the microphysical environment of ice accumulation. Using airborne particle detection equipment produced by DMT, physical quantities such as detected cloud particle number concentration, average volume diameter and liquid water content were calculated to analyze the microphysical characteristics of an aircraft cumulus cloud system in the Sichuan Basin on December 13, 2015. The results show that the cloud system can be divided into three layers, among which the upper and middle clouds are rich in supercooled water content, exceeding 0.1 g /m3 and 0.25 g /m3, respectively, with large cloud droplet number concentration and smaller cloud droplets in the upper layer and smaller cloud droplet number concentration and larger cloud droplets in the middle layer. Ice accumulation occurs at heights where supercooled water is abundant but varies greatly with time, with a maximum value of more than 0.35 g/ m3 and a low concentration of ice crystals, which is conducive to the maintenance of supercooled water.