Abstract: A new type of fiber optic sensor is developed for detecting the pore-water pressure in freeway foundation, which is embedded in the foundation of the Guang-Wu freeway to monitor construction of soft soil foundation. Fiber optic Bragg gating is contained in these sensors to detect the value of the pressure exactly and become sensitive to fluctuating of the water pressure. In this experiment, problems of the building, embedding and data collection etc of the measuring system are solved. In order to appraising the new sensor, we compared the collected data of the fiber optic sensor to those of the conventional sensors. By analyzing the data collected, we appraise the effect of soft soil foundation treatment, then compare the result to the actual situation to find whether the sensors reflect the real condition. The result shows that these sensors can not only achieve the same effect of the conventional sensors but also overcome some deficiencies of the conventional ones, and the development of this new fiber optic sensor is successful.