Exploring the effect of droplet velocity on the behavior of binary droplets of the same size colliding head-on on a superhydrophobic surface, pure water droplets were used as the research object. The collision process of droplets was observed with a high-speed camera, and a theoretical model of the critical conditions for coalescence or bouncing after collision was established. The model can predict the critical velocity for coalescence or bouncing after droplet collision. The results show that with the increase in droplet velocity, the probability of droplet coalescence after collision increases; the larger the droplet size, the lower the critical velocity for coalescence or bouncing after collision. During the deformation process of droplet collision, the internal pressure increases beyond the limit that surface tension can withstand, resulting in droplet coalescence. The theoretical method established matches the experimental results well. The proposed theoretical model can be used to predict the behavioral changes of droplets at a certain velocity, achieving the purpose of controlling droplet collision behavior, and can be applied to fields such as droplet manipulation, droplet sensing, and microreactors.