Loosely coupled transformer is an important device for realizing electric energy transfer in inductively coupled power transfer (ICPT) system. However, the low transmission power and low transmission efficiency of loosely coupled transformer greatly limit its application. Three-terminal shaft loosely coupled transformer structure was proposed, and a mathematical model was established respectively for the two cases where adjacent coils of the new transformer have the same direction and reverse end. Then, the frequency splitting phenomenon of the ICPT system based on the three-terminal shaft loosely coupled transformer under the LCC-S compensation method was analyzed. The simulation verifies that the three-terminal shaft loosely coupled transformer can improve the transmission characteristics of the system through the mutual inductance between different coil pairs, and compares the transmission power and transmission efficiency of the same direction and the reverse of the same end. Finally, the experimental results show that the ICPT system based on the three-terminal shaft loosely coupled transformer can improve the transmission power and transmission efficiency, and the transmission efficiency is higher when the same end is in the same direction, which increases by 16.4%. When the same end is reversed, the transmission power increases by 33.2%.