Based on the localization requirements of mobile robots in unstructured environments, the development history of mobile robot localization research was systematically reviewed. It can be divided into three stages, such as accumulation of experience, formation of theoretical framework and breakthrough of applied research. Three main contradictions driving the development of mobile robot localization technology were pointed out. The advantages and disadvantages of the algorithms used to solve the key problems were compared and summarized. The key research directions of mobile robot localization based on vision were prospected.