In view of the problems such as the low measurement accuracy, single measuring parameter, large sensor volume are exist in the traditional flow measurement, and a multifunction integrated flow sensor based on fiber Bragg grating (FBG) is designed. The multifunction flow measurement using FBG differential pressure type flow measurement as structure body, and integrating FBG temperature and pressure sensor, thus the fluid flow, pressure and temperature are measured at the same time. On the base of introducting the FBG sensing principle, the capillary tube packaging FBG sensor and the blind-piple FBG pressure sensor working principle are analyzed. Meanwhile, on the basis of analysis the sensing principle of differential pressure type FBG flow sensor, the structure and realize principles of the multifunction FBG flow sensor are introducted. Using water bath, pressure gauge calibration meter and integrated flow test plantform, which test the sensing charactors of the FBG temperature, pressure and flow sensor within the multifunction FBG sensor. According to the test results, the sensitivity of FBG temperature sensor is 0.015 nm/℃, the sensitivity of FBG pressure sensor is 0.028 nm/MPa, and the sensitivity of FBG flow sensor is 0.068 L/s. At the same time, the temperature sensor is used as a reference, which can solve the temperature inter-sensitive effect in the FBG pressure and flow measurement.