Coverage control is a fundamental problem for wireless sensor networks, which has been explored thoroughly in the networks based on an omni-directional sensing model. Recently, thanks to the introduction of image/video, infrared, ultrasound sensors, coverage control algorithms for directional sensor networks have drawn more attention and have become a focus. This paper starts from the concept and characteristics of directional sensing model, and then summarizes the current research progresses at home or abroad. The study also classifies and summarizes the basic coverage control theories and algorithms in the context of directional sensor networks. Finally, the paper points out the open research problems to be solved and the future trends.