A demodulated method for fiber Bragg grating (FBG) pulse wave is proposed based on micro-structure Fabry-Perot interferometer (MS-FPI). The proposed MS-FPI is fabricated by splicing single mode fiber and photonic crystal fiber (PCF), and the micro-bubble structure is formed near the splicing end face by the special technology to constitute the Fabry-Perot (F-P) cavity, whose size is about 48 μm. In order to increase mechanical strength, the MS-FPI is coated again and thus can be woven into the fabric as yarn. Its interference spectrum remains nearly unchanged even its bending diameter is up to 4 cm. Besides, it also has very low temperature sensitivity, suitable as a demodulator filter. The proposed demodulated method is analyzed theoretically and studied experimentally. The results indicate that the designed demodulated system achieves linear demodulation in the range of the FBG pulse wave and has better measurement repeatability. The demodulated sensitivity is about 43 mV/pm. The demodulated pulse wave is consistent with the result of the commercial interrogator. By comparing with the photoplethysmography, the correctness of the pulse wave demodulated by designed system is proved.