Abstract: A novel five fingered robotic hand is developed based on underactuated adaptive theory, which has the similar size to that of an adult hand. The underactuated adaptive robotic hand has a simple mechanism and light weight. It has strongly adaptive speciality, and can be used as end effectors of humanoid robots and as the prosthetic hand. A quasi static model of a 3 DOF underactuated finger is built based on virtual power theory.