A miniature fiber-optic Fabry-Perot interferometer (MOFPI) fabricated by splicing a hollow silica tube (HST) with inner diameter of 4 μm to the end of a single-mode fiber is investigated and experimentally demonstrated. The theoretical relationship between the free spectrum range and the length of HST is verified by fabricating several MOFPIs with different lengths. We characterize the MOFPIs for temperature, liquid refractive index, and strain. Experimental results show that the sensitivities of the temperature, liquid refractive index, and strain are 16.42 pm/℃, -118.56 dB/RIU, and 1.21 pm/με, respectively.