The design of a polarized optical pressure fiber sensor system is presented. The system mainly consists of a laser, a birefringent crystal, a quarter wave plate, two polarizers, a sensing element and two photodetectors. The design of the sensing element is based on the photo-elastic effect. This type of sensor can be used to detect pressure, force and weight of an object. In addition, the sensor can be used to detect and to monitor the condition of overload of a vehicle real time and on line.