A miniature extrinsic Fabry-Perot (F-P) interferometer (EFPI) sensor is fabricated by using simple etching and fusing method. The cavity is formed by wet chemical etching of multi-mode fiber (MMF) in hydrofluoric acid based solutions,then it is fused to the end of a single-mode fiber (SMF) to form a extrinsic F-P structure. Experiment results show that this kind of EFPI sensor has a high sensitivity to strain,but a low sensitivity to temperature. The strain sensitivity is about 0.00095 nm /μ ε. This kind of fiber sensor has many advantages,such as easy fabrication,high-repetition and mass-production,which offers great potential for sensing applications and especially for strain measurements in health monitoring of civil engineering structure.