Abstract: This paper deals with the actuation of magnetic endoscopic robot capsule by external magnetic field. We combine the gradient coils with the homogeneous coils, and then adjust their current-loads and rotational movement around a translatable patient bed, so as to compose a particular magnetic field of which the spatial gradient is uniform and the low-intensive area can be adjusted dynamically. The magnetic field acts on the permanent magnet embedded in the capsule, and generates the desired drive force and aiding torque. The simulation indicates that the particular magnetic environment caused by the combined coils is beneficial to drive the robot. The proposed driving method has good controllability and safety, and lays a foundation for studying micro-robots drived by external gradient magnetic field in various tracts.