In this paper, we present the design of a polarized optical pressure fiber sensor system, which consists of a laser, a birefringent crystal, a quarter-wave plate, two polarizers, a sensing element and two photodetectors, etc.. The design principle of the sensing element is based on the opto-elastic effect in the system. This type of the sensor can be used to detect the various pressures, forces and weights of the objects, etc., and to detect and to monitor the overland for the vehicles on real time and on line, especially.