Based on the airborne observation data obtained by the Particle Measuring System (PMS) in Sichuan Province on 24 October 2008, the characteristics of the autumn lowlevel warm clouds without ground precipitation are discussed. The results show that: (1) The lowlevel warm clouds were composed mainly of small cloud droplets, and the number concentration of large cloud droplets was relatively low, and the precipitation particles in the clouds were very few.(2) The liquid water content, number concentration and diameter of small cloud droplets were inhomogeneous in horizontal direction.(3) There was a positive correlation between the liquid water content and the mean diameter of small cloud droplets.(4) Compared with the upper layer of the clouds, there were less small cloud droplets and large cloud droplets (small raindrops) and fewer large raindrops in the cloud base.(5) Because of the small cloud liquid water content, thin cloud thickness, difficult condensation growth of cloud droplets, inactive coalescence growth, and short path and time of collision growth, there was no precipitation reaching the ground.