A new miniature extrinsic Fabry-Pérot (F-P) fiber optical pressure sensor based on fiber fusion and F-P interference is developed. It is made of commercial single-mode fiber and graded-index multimode fiber. Its all-silica structure has good stability for long-term use. The sensor is fabricated by simple techniques involving only cleaving,wet chemical etching and fusion splicing. The relation among the diaphragm thickness,the different cavity radius and the sensitivity is simulated,and the diaphragm thickness and the cavity depth are obtained. The processing step is designed. The key technologies,fiber etching and fiber splicing are discussed. By tracing a peak point in the interference spectrum,the gap length of the sensor can be demodulated. The demodulation system is set up. Experimental results demonstrate that a high linear response in the range of 0 to 0.1 MPa is obtained in this sensor.