Abstract: This paper presents an experiment based on the optical fiber Fabry-Perot (F-P)interferenceprinciple．A high-precision weak-pressure measurement system was designed and constructed． The systemconsists of a spring-based pressure-deformation module，an F-P optical fiber displacement measurementmodule，and an algorithmic processing system based on a PC-end LabVIEW platform． The displacementmeasurement module calculates the cavity length variation by demodulating the wavelength difference betweenadjacent valleys in the interference spectrum．Spring’s elastic coefficient is then derived from the applied massof calibration weights．This calibrated coefficient enables the system to measure the mass of arbitrarily smallobjects．Experimental results indicate that the system exhibits good linearity within the 0 ～ 500 mg range．For
objects heavier than 20 mg，the maximum measurement error is approximately 5%，and the error decreases as
the mass increases．The proposed system features a simple structure，low cost，and high measurement accuracy，
offering a feasible optical method for high-precision weak-pressure measurement．
