Abstract: A micro-motor-based micro-robot,which can move in intestinal tract,is designed.Based on the analysis on the gait,the locomotion of this robot including wriggle in the axial direction,and expand-contract in the radial direction,and the corresponding mechanism is designed and realized.An experiment is made to prove the feasibility of the axial design. The assembled robot isφ13 mm×50 mm in size,with the function of 10 mm axial stepping and 8 mm radial expanding and contraction.