Abstract: Localization is the process of finding the position and orientation of the robot. Reliable localization based on sensors is one of the most fundamental and important tasks for autonomous robots. This paper reviews the relevant indoor mobile robot localization technologies, presents a general control architecture, and especially introduces the problem of map building and pose estimation. The methods and open problems of map building, global localization, data association, SLAM (Simultaneous Localization and Map Building), information fusion and collaborative localization are also mentioned.