In order to meet the demodulation requirements of dynamic pressure better, a diaphragm-type optical fiber dynamic pressure sensor based on Fabry-Perot (F-P) interference principle is studied. The influence of multiple reflective surfaces on the spectrum of the F-P cavity is theoretically analyzed, and a method is proposed to obtain a single F-P cavity. The outer surface of the sensor diaphragm is roughened by mechanical grinding, which effectively solves the complex spectrum problem caused by multiple reflective surfaces. Static pressure and dynamic pressure calibration tests are carried out on the sensor, and the results show that the sensor performs well. The static pressure measurement error of the sensor in the range of 0-200 kPa (gauge pressure) is not more than 0.5 %FS, and the amplitude sensitivity relative error of the sensor does not exceed ±10% within the range of 20~2500 Hz.