Abstract: This study describes the development and relevant issues of a new cloud droplet probe based on Mie scattering and laser technology. A small pin-hole orifice is used to simulate the light scattered to determine the sensing area for the system. Calibration is precisely done by adopting standard spherical samples with different diameters as the replacements of different size cloud droplets to obtain the system response curve, so the droplet size and concentration of cloud particles can be determined. After a series of experiments were finished in laboratory, put the probe on the airborne to do the cloud experiment, and the airborne experiments demonstrate that the new cloud droplet probe works reliably and stably, and it can show the droplet size and concentration of cloud particles in sensitive areas immediately. Analysing the stored data, calculating the number of the particles, and comparing with the droplet size in cloud, the results showed that the data is effective and reliable, the system has good capacity to probe the cloud.