As the most common and basic robotic movement in environment such as factory and household, the autonomous grasping has various application prospect. Although researchers have paid higher attention to the robot autonomous grasping in recent decades, grasping arbitrary objects accurately with arbitrary poses in non-structural environment is still a challenging and complex study. The robot grasping involves three main aspects: sensing, planning and controlling. The first step is detecting the targeted object and generating the grasping pose. It is the precondition of the successful grasp that helps achieve the grasp path planning and the entire grasp movement. The literature review in this study is mainly based on sensing. Firstly, the grasping technology is introduced from two aspects: analytical method and empirical method, and the empirical method is divided into the grasping of known objects and unknown objects from the perspective of whether there is prior knowledge of grasping objects. Moreover, the typical grasping methods and their related features contained in each category of unknown object grasping is detailly described. Finally, the development direction of robotic grasp detection technology is prospected with the aim of providing references for the relevant researchers.