Studies in green hospitals and related topics are still in the very beginning stage in Taiwan, as well as greening work has just started in most hospitals in Taiwan. To speed up the spreading and deepening of green hospitals, understanding the minds and behavior of patients on hospital can be a good start. Using the theory of planned behavior as fundamental framework, this study aimed to discover the influencing factors on intention of patients toward hospital. A survey was used to interview 620 patients in the participant hospital. The result showed below. The green hospitals scale has stable reliability and validity through two stage tests. The items of green hospitals include Energy efficiency, green building, food, waste and water can influence the attitude of patients. Attitude, subjective norms and perceived behavior control were also factors of intention of patients. The survey were analyzed using a green hospital scale in a two-stage test, and the result showed stable reliability and validity. Influencing factors on attitude of patients toward green hospitals include energy efficiency, green building, food, waste, and water. Attitude, subjective norms, and perceived control were also factors on intention of patients.