Abstract: Autonomous map building of mobile robots is a fundamental and important problem in research on robotics. This paper surveyed the lasted progress in the field, specially uncertain information based map-building in absolutely unknown environment. Map-building's method for single robot is first introduced, and some key techniques are analyzed in detail, such as map representation, navigation, description and process of uncertain information. Map-building by multi robot's collaboration is introduced according the newest literatures, too. The main problems on map-building research are mentioned, in the meanwhile, the further research and development trends are discussed.