In this paper,a narrow channel microflow velocity and temperature meas urement system based on FBG embedded in Sagnac ring is proposed.The lateral pressur e of the polarization-maintaining fiber (PMF) sustained varies with the microflow rate,a nd the microflow velocity is achieved by monitoring the output wavelength shift of the fiber Sagnac ring.I n addition,the fiber Bragg grating (FBG) embedded in the fiber Sagnac ring is sensitive to the temp erature,which is used to achieve the environmental temperature.In experiment,the narrow channel is simulated by capillary,and the polarized fiber in the fiber′s Sagnac ring can be fixed by the capillary.Then,the range of microflow rate can be obtained by microflow pump.The experimental results show that the lateral pressure for PMF will change with the microflow velocity, resulting in the Sagnac interferometer wavelength shift.When the microflow v elocity changes in the range of 0－450μm/min,two resonance peaks at 1522.47nm and 1544.64nm are monitored and the average sensitivities are 5.59pm/(μm/min) and 5.98pm/(um/min),resp ectively.In addition, the temperature sensitivity of the sensor is 9.74pm/℃ with the ambien t temperature increases from 20℃ to 45℃.The sensor owns several advantages,s uch as wide measurement range, high sensitivity,simple structure,easy manufacture and low cost,and it has gr eat practical value.