Rain removal from videos is among the key technologies in image processing and video surveillance because of the complex visual effects caused by rain. With the rapid development of computer vision technologies, rain removal has attracted increasing interests in both academic and industrial communities. In this paper, we firstly reviewed the main rain removal methods by classifying them into four categories based on the exploited rain properties. Some possible Challenges are also pointed out. And then, some constructive suggestions and prospects for the future research are brought forward.