The purpose of the article was to understand the development of the mindfulness in sports and to apply the mindfulness skill to tennis. Due to the many different attributes of tennis, athletes need to overcome their emotional changes by themselves. The meaning of the mindfulness skill was to alter pessimistic thoughts and strengthen attention and awareness. The previous studies also demonstrated that the mindfulness skill can help athletes enhance performance, alter pessimistic thoughts, and improve awareness, attention, and concentration in order to make the best decisions without emotional interference (Kabat-Zinn, 2003). Therefore, it is recommended that mindfulness training should be emphasized in tennis training.