Abstract: Computer vision based pedestrian detection has become one of the hottest topics in the domain of computer vision and intelligent vehicle because of its potential applications in driver assistance systems. It aims at detecting pedestrians appearing ahead of the vehicle using a vehicle-mounted camera, so as to assess the danger and take actions to protect pedestrians in case of danger. In this paper, we give detailed analysis of the diffculties lying in the problem and review most of the literature. A typical pedestrian detection system includes two modules: regions of interest (ROIs) segmentation and object recognition. This paper introduces the principle of typical methods of the two modules and analyzes their respective pros and cons. Finally, we give detailed analysis of performance evaluation and propose some research directions.