In order to overcome the shortcomings of the existing artificial heart: it needs a passageway through the skin for the energy supply and its energy conversion components give out heat in the human body, we use the active and passive permanent magnet as a non-contact driving device for a blood pump. Taking the distance between the heart aorta and the outer surface of the body into account, the space interval between the active and passive magnet must reach about 100 mm, so the torque that they can transmit is very small. This paper presents a non-contact power transmission system with three permanent magnets for artificial heart, which consists of active magnet and the first and second passive magnet. In this paper, we have analyzed and calculated the magnetic field distribution and driving torque of the three permanent magnet system using three dimensional finite element method. The results show that the three magnet system can transmit much greater torque than the two magnet system. Apart from the power transmission system for artificial heart blood pump, the three magnet system can also be used in other non-contact driving device.