Through the combination of experimental measurement and CFD (computational fluid dynamics) method, the fluid flow characteristics in the pipe of magnetic capsule robot for intestinal tract are studied. The PIV (particle imaging velocimetry) system is used to measure the fluid flow field around the magnetic-controlled capsule robot under certain translational and rotational speeds, and the rich flow field information (streamline, velocity, and vorticity) is obtained. At the same time, the CFD software is used to calculate the corresponding flow field and the force acting on the capsule robot, and the calculated value is basically consistent with the experimental value. The results show that, driven by the external permanent magnet, the magnetic capsule robot makes corresponding precession movement in the pipe filled with silicone oil, and the movement track is wavy. When the pipe diameter is increased, the fluid streamline around the capsule robot is more stable, the vorticity value is smaller, the resistance and resisting moment of the capsule robot in the forward direction become smaller. The PIV measurement method and CFD method used in this paper can be applied to the fluid flow field measurement and mechanical analysis of the smaller size capsule robot in the liquid environment.