One of the natural mechanisms in the clouds for the formation of rain drops, after the process of condensate growth of the primary nuclei of the cloud, is the mixing of the cloud droplets. Mixing is the most important processes involved in the formation of rain drops. One of the modern methods to increase the mixing of the droplets is the use of the sound waves. At present research, mixing of droplets in two types of cold and warm clouds are theoretically investigated using sound waves with various frequencies. The results show that the mixing of droplets decreases with increasing frequency. Also, the results of modeling show that temperature decrease in cloud leads to an increase in the mixing of the droplets. As a result, the use of sound waves in a cold cloud will have more efficiency than the warm cloud.