A preparation method of a novel optical fiber F-P cavity sensor device, comprising the following steps: take a section of optical fiber, peel off the coating layer to obtain a section of bare optical fiber, clean it with alcohol, and cut the bare optical fiber along the middle with an optical fiber cutter; Fix it on a glass slide, place the slide on a three-dimensional precision micro-displacement platform, adjust the three-dimensional micro-displacement platform so that the laser spot focus position coincides with the end face of the bare fiber, and then move the micro-displacement platform outward along the fiber axis to focus the light spot The position is far from the end face of the bare fiber; adjust the pulse frequency of the excimer laser, turn on the excimer laser, pressurize, turn off the laser, and make a sensor; get a square microhole at the top, and clean the impurities in the hole with hydrofluoric acid solution , a sensor for simultaneous measurement of pressure, temperature and liquid refractive index was fabricated. The tip of the sensor made by the invention has strong structure, small volume, simple manufacture, low cost and good measurement accuracy for temperature, pressure and refraction index.