Abstract: In order to simulate the 3D motion and micro-manipulation of the robot in human body environment, a 3D motion and micro-manipulation method of the millimeter-scale submarine-shaped robot in horizontal attitude is proposed in low Reynolds number liquid. Firstly, the submarine-shaped robot and the 4-coil magnetic drive system are designed and fabricated, and the finite element simulation of the magnetic field system is carried out by COMSOL software. Then, the forces on the robot in low Reynolds number liquid are analyzed, and the robot motion model is established. Furthermore, its various motion forms are studied. The robot can perform 3D motion along a specified path in low Reynolds number liquid, such as vertical up motion, diagonal rising motion, right angle motion and spiral upward motion, while maintaining its horizontal attitude, and the maximum speed is 1.2 mm/s. With the developed wireless electrical energy transfer system, electrical energy can be transmitted into the small-scale environment. With the wireless electrical energy, the robot can drive the gripper in its front end to perform micro-manipulations such as gripping, carrying, and releasing.