Abstract. In order to promote the movement inside tunnel robot in the cable tunnel and obstacle capability, designed a swing arm type crawler chassis, applied to the robot. The chassis adopts the modular design, assembly simple replacement maintenance convenience, enhances the terrain adaptability. Swing arm type caterpillar chassis adopts the former independent form of swing arm, using crawler swing arm Angle before climbing movement, before the swing arm can rotate at any Angle, boosting the terrain adaptability. Two walking tracks the independent motor drive, can achieve differential steering, a is a counter can be realized in situ 360° rotation, can make the chassis in the narrow space free to; And simplify the traditional crawler chassis production complexity, strong load capacity at the same time.