Even though there are numerous theories to explain the process of rain, it is not enough to do adequately. According to observation, the precipitation from the rapidly formed cloud, like squall or shower, has not been understood clearly. Generally, a relationship between droplet and nuclei or between droplets are well known reason for this phenomena and still challenging research part. Especially, in tropics, the relationship between droplets is more important than the other due to temperature. Hence, in this research the numerical simulation between droplets within gravity force field like the earth has been performed. The objective of the research is not only to identify physical properties but also to figure out droplets itself and nearby flows, hence, the Level Set method has been used to track the interface of droplets correctly. The result is verified using existing work, droplet collision without gravity force, and using this model we’d like to show collision