The end-force measurement of minimally invasive surgical puncture probes is crucial for achieving precise control of such probes， improving the quality of surgeries， and ensuring the safety of surgical operations. In this study， a fiber optic force sensor with a Fabry-Pérot （F-P）-cavity-cascaded fiber Bragg grating （FBG） that can be integrated into the probe is designed to meet the actual requirements for measuring the force at the end of a puncture surgical probe. First， based on the double-beam interference theory of the F-P cavity and fiber grating sensing theory combined with the cantilever beam structure of the probe， the F-P cavity and FBG of the fiber optic sensor implanted in the probe sensing model are analyzed. Then， the mapping relationship between the characteristic wavelength shift of the F-P cavity and the FBG and the applied force are deduced， with the force and temperature sensitivity matrix being introduced to realize the probe force measurement while effectively avoiding the cross-influence problem of temperature. Next， the optical-fiber F-P-cavity parallel-cascade FBG constitution sensor is prepared by employing chemical corrosion， and the sensor is integrated into the surgical probe. Finally， to calibrate and verify the F-P-cavity-cascaded FBG fiber optic force sensor， the force and temperature sensitivity and the stability of the sensor are experimentally tested. The experimental results show that the force sensitivity of the fiber F-P cavity of the sensor can reach 331.8 pm/N， FBG force sensitivity can reach 159.9 pm/N， linearity is >0.99， and average wavelength shift is 2.5 pm. The probe force sensor designed in this study has high sensitivity and good linearity， thus exhibiting broad application prospects in the field of minimally invasive surgical puncture robots.