The paper introduces the concept of ward calling system for hospital and Internet of Things (IoT) in healthcare, elaborates on the building of an intelligent mobile calling system based on IoT from three aspects of calling system networking, building of private 4G network, optimization of software and function. It points out that such a system can realize the two-way vocal communication between physicians and patients, nurses and patients, physicians and nurses in real time, which will facilitate the improvement of healthcare services.