A novel micro cantilever-based hydrogen sensor with fiber Bragg grating(FBG) for detection of hydrogen was developed. The deflection of microcantilever due to absorption of hydrogen was measured by the wavelength shift of FBG,then,the content of hydrogen can be inferred. The stress transfer model of the sensor is analyzed based on elasticity theory. The relationship between the Bragg wavelength shift and the saturation hydrogen content is derived,and it shows that the sensitivity of the sensor can be improved by changing the thickness ratio of palladium and silicon cantilever beam and the maximum wavelength shift is obtained as thickness ratio is 0.4. The response of the sensor to hydrogen was measured. The analytical value was close to the experimental result.