Position feedback element as the critical part of servo control system, the feedback accuracy directly affects the control precision of the whole system. In this paper, a novel redundant linear displacement sensor is proposed. An axial magnetized cylindrical pole with exacting length-to-diameter ratio is adopted to be the linear magnetic field source, which is assembled in the central sleeve of the linear sensor to realize reciprocating linear motion. Mutually redundant position detection circuits are mounted symmetrically on both sides of the moving magnet, on which six hall elements are linearly arranged to accomplish large stroke of the sensor. The magnetic flux density in radial and axial direction of the moving magnet is detailedly modeled based on magnetic potential vector (MPV) and compared with the finite element methods (FEM). Then, position detection principle is introduced depending on the six hall elements and position solution method of whole stroke is presented. Finally, experimental prototype is built and linearity error of the sensor is validated better than 0.7% compared with linear potentiometer within the 50mm stroke range. This novel design provides complete guidance for sensor design with high reliability, long lifespan, reconfigurability and miniaturization. Moreover, it is convenient to be integrated design with whole servo system applied in limited space and harsh environment.