Directly self-adaptive under-actuated (DSUA) hands have great potential to stably grasp different objects in unstructured environments. This paper develops a DSUA Hand based on multi-pulley-belt mechanism, which consists of 5 fingers and has 14 DOF. Self-adaptation is designed as the main function of it. The stability of DSUA hand’s grasping process does not highly depend on control algorithm, sensors or control system. This DSUA fingers are based on multi-pulley-belt mechanism. A mathematical model of the 3-joint finger’s contact force is given. Contact force analyses of the DSUA finger are discussed in detail. DSUA Hand weighs 0.94 kg and can grasp objects up to 0.6 kg. The grasping adaptation of DSUA hand is certified by grasping experiments of different objects.