A novel high sensitivity diaphragm-based extrinsic Fabry-Pérot (FP) interferometric fiber-optic pressure sensor with back-pressure equilibrium structure is present. The sensor possesses backpressure-independence and small temperature-dependence. The ultra-thin fused silica is bonded to the end surface of the double holes fused silica ferrule by use of CO2 laser, and the double holes structure enhances the sensor performance. The operating point does not drift. The sensor with sensitivity of 9.51 nm/kPa (65.57 nm/psi) has been achieved.