According to special requirement of seepage monitoring in engineering and model experiment of dams,tunnels and coal mines,a novel optical fiber Bragg grating (FBG) based seepage pressure sensor is designed and fabricated. A draw-bar structure and a corrugated diaphragm are adopted to change the axial strain of optical fiber grating. The diaphragm pressure characteristics and sensor′s shell resistance characteristics are simulated and analyzed by using the finite element software ANSYS respectively,which can shorten the design cycle and improve the reliability of the sensor. Calibration experiments show that the pressure sensitivity of the sensor is 20 nm/MPa in the range of 0-100 kPa,which is 6683 times higher than that of ordinary optical FBG. The hysteresis and repeatability experiments indicate that the hysteresis factor is 0.85% and the sensor has good reproducibility.