This paper describes a newly developed position sensor system. The position sensing system is designed to be combined with the radial permanent magnetic bearing and used for the control of the axial active magnetic bearing. The rotor ring of the radial magnetic bearing is used as field source, which shortens the rotor and saves space for artificial heart design. Linear hall sensor is selected due to its low cost and miniature size. The principle of the position sensing system is based on the analysis of the magnetic field of the permanent magnetic bearing and the sensor module is designed via finite-element analysis to optimize sensitivity and accuracy of the measured signal. An applied primary amplifier circuit for the position sensing is designed and its performance is tested. The experimental results demonstrate that the position sensing system has a satisfactory performance and is effective for axial control.