Abstract: A main body structure of a submarine stratum space cable laying robot includes one telescopic electric linear actuator unit including two dustproof sleeves with one sleeved on the other, and four single supporting arm units for forward motion and supporting. Two ends of each single supporting arm unit are sequentially provided with rotating supporting plates, reducers, motors and connecting flanges from inside to outside, and an outside of each single supporting arm unit is provided with a rotating plate structure. The single supporting arm units in each group are movably connected by the adjacent ends and movably connected to connectors of the telescopic electric linear actuator unit by respective outer ends thereof. The two groups of single supporting arm units connected in series are symmetrically arranged, such that a whole main body structure of the robot is diamond-shaped.