This paper presents a way for research on three-fingered robotic grasping plan. According to the assortment of human hand graxping, two typical robotic grasping poses for three-fingers grip are summaried. Then the task requirements,the geometrical and physical features of the object and the information from the environment are synthesized. Grasp pose is deduced by task analysis, and the graspable plane is sought and determined. The grasping plan process is finally carried out by determing three grasping points on the graspable plane.