Multi-dimensional wireless power transmission is the key to the development of gastrointestinal capsule robots. To solve the problem that the functions of new capsule robots are increasing, and the traditional three-dimensional receiving coils take up too much internal space, this article proposes a three-dimensional combined transmitting coil that is able to generate a dynamic three-dimensional magnetic field by modulating the currents passing through each dimensional coil. Firstly, the working principle of the wireless energy supply system is introduced. Then, a finite element analysis of the spatial magnetic field generated by the transmitting system is implemented. Finally, experiments are conducted by using the constructed platform to evaluate the accuracy of the simulation results and determine the attitude of the receiving coil to sense the maximum receiving voltage. The experimental results show that the load-received energy exceeds 630 mW when the transmitter system generates equal three-dimensional magnetic field components at the center point. In addition, the positional stability of the edge region near the transmitter system exceeds 80%, which ensures that the capsule robot can operate smoothly.