Abstract: As one branch of WSN and important part of the Internet of Things, Body Sensor Network(BSN) is utilized to improve people's Healthcare and Medicine by pervasive computing, intelligent information processing, new network technologies and services. So, it is paid more and more attention to by researchers and enterprises. Existing survey researches have given full discussion on the advances and challenges of BSN's biosensor, wireless communication architecture and data security. However, focused on in this paper are BSN's data fusion, context-aware sensing, and system technologies from perspectives of technology challenges, research advance and development trend. It introduces basic concepts and research situation of BSN are introduced. Besides, BSN's system architecture, representative applications and research projects are introduced. At the same time, future research and application prospects of BSN are given. Some practical problems about restriction on BSN research and development are also presented. The contributions are to propose the BSN architecture, analyze the challenges of BSN, and point out the practical problems restricting BSN's development. Through studying abundant references and designing effective introduction structure, the hot and key scientific issues about BSN are given clearly and thus helps other researchers, especially beginners, to know BSN's situation well. At last, although lots of challenges still exist, the developing trend of BSN will be that multi-techniques are integrated to achieve intelligence, effectiveness and usability of it. And, BSN will become an inevitable choice for future healthcare monitoring service.