We propose a miniaturized fiber optic fabry-perot pressure measuring system, which consists of two parts: ultra-high pressure sensor with embedded MEMS Fabry-Perot cavity and miniaturized phase demodulation system, for marine pressure measurement. The ultra-high pressure sensor have been analyzed and proved to meet the requirements of the full ocean pressure measurement by analyzing mechanical and optical characteristics. In order to meet the application demands of marine pressure measurement, the pressure fatigue test and hydrostatic pressure test have been carried out. The test results show that the pressure measuring system has a stable response relationship between the absolute phase and pressure in the range of 2–120 MPa, and no significant changes was found neither in four consecutive months of ultra-high pressure tests. The repeated error of system is less than 0.012MPa at 60MPa. The miniaturized measuring system can be applied to the ocean profiling measurement plan named the Argo plan.