Abstract: Cyber-physical systems (CPS) are integrations of computing and physical systems. Through embedded computers and networks, CPS has realized the cooperation and fusion of these two systems. It will pose great impacts on way of life and mode of production. CPS is a brand new research area, and many problems still need to be solved when utilizing the existing theories and technologies to construct it. Firstly, the concept, characteristics and architecture of CPS are summarized, and its relations with embedded system and network are analyzed. Then, from the perspective of computing system, network system and control system, the main challenges that CPS met are discussed, and currently available theories and technologies that can be utilized in CPS design and the most recent research advances of it are surveyed. Finally it is proposed that the CPS development of the next step should be led by solving the problems of systems abstraction layer design, modeling, architecture design, data transferring and management and system integration as the main research directions, and also offers the possible solutions for those key problems.