The invention belongs to the field of electromechanical technology, and relates to a spherical mobile robot, in particular, to a fluid-driven spherical robot, which includes a spherical shell, an annular sealed container, an axial flow device, an internal drive rotation mechanism, and a main shaft; it is characterized in that: the spherical shell is composed of The left and right hemispherical shells are composed of two hemispherical shells; the annular sealed container is located inside the spherical shell, the outer ring surface of the container is concentric with the spherical surface of the spherical shell, and the fluid is contained inside the container, and the volume of the fluid is 1 / 2 of the volume of the container. The axial flow device drives the liquid to flow in the annular sealed container, thereby changing the center of mass of the spherical robot, thereby realizing the forward and backward of the spherical robot; the internal drive rotation mechanism located inside the spherical shell mainly includes: internal drive bracket, motor, Motor bracket, flywheel shaft, flywheel, power supply and controller, etc.; the main shaft is connected to the spherical shell through bearings, other parts of the internal drive rotation mechanism are suspended on the main shaft through the internal drive bracket, and the motor is fixed to the internal drive bracket through the motor bracket Connection, the flywheel is installed on the internal drive bracket through the bearing, the motor shaft and the flywheel are connected through the coupling, the motor drives the flywheel shaft and the flywheel whose lower part is perpendicular to the main shaft to rotate together, and realizes the steering of the fluid-driven spherical robot by using the principle of conservation of angular momentum .