The invention discloses a miniature extrinsic optical fiber Fabry-Perot pressure sensor, and aims at providing the pressure sensor which is stable in performance, high in overall intensity and low in cost and can enhance interference signal intensity, reduce noise and eliminate warping caused by silicon chip and glass thermal expansion difference. The miniature extrinsic optical fiber Fabry-Perot pressure sensor is realized by the following technical scheme that a pressure sensing chip is composed of a three-layer structure formed by a high borosilicate glass sheet 4 equipped with a step hole recessed cavity, a high borosilicate glass sheet 10 and a silicon chip 6 which is clamped between the high borosilicate glass sheet 4 and the high borosilicate glass sheet 10 so that a double-layer cavity structure of a Fabry-Perot cavity and a ventilation cavity 5 separated by the silicon chip is formed. The pressure sensing chip is assembled on the end surface of an optical fiber inserting core, and the pressure sensing chip and the optical fiber inserting core are connected together. The ventilation cavity and the Fabry-Perot cavity of the two sides of the silicon chip apply different air pressure to the silicon chip, the pressure in the Fabry-Perot cavity is basically maintained to be constant, the deformation of the silicon chip can be detected and then external pressure detection can be realized.