The principle of continuous ink jet printing is to run droplets into printing paper. It is difficult, however, to form stable droplets, and moreover, unstable droplets cause decline of printing performance. The purposes of this research are both to analyze droplet formations and to solve control factor of split process from ink column into droplet by using CFD. The results show that the satellite droplets has not appeared, and that both formation process of droplet with long tail and the growth of swirl in nozzle part have been shown in this simulation condition as time passed by. In conclusion, it is necessary for us to study both how the long tail of droplet changes and how the swirl in nozzle part influences droplets.