Abstract: In order to enter into human body and fulfill tasks there,a prototype of 6 millimeters in diameter for the earthworm-like micro robot with multiple joints is developed.The linear driver is connected with one another by cross shape universal joints.The robot can adaptively adjust itself in the curved cavity.A feed-forward compensation control algorithm for shape memory alloy deflection mechanism is presented based on Preisach model and deflection model,and the maximal reflection error of the head carbin is less than 2.6°.Locomotion model is created based on new creeping principle,and the conditions of efficient driving are given.Experiments are made on locomotion force,velocity,locomotion ability on surfaces with different friction coefficients,and pose of the head cabin.It is found that the ability of creeping up a slope depends on friction coefficients between the surface and the robot,the new creeping principle can provide larger locomotion force,and larger velocity can be got when frequency of the driving signals is appropriate.