Abstract: A demodulation method for measuring the pressure with the fiber Bragg dualgrating is put forward to improve the precision of fiber Bragg grating (FBG) pressure sensors and reduce the cost of the measurement systems. Under the action of external pressure, the reflected wavelength drift of sensing FBG is transformed into time interval variation of light pulse reflected by the grating, which is modulated by means of driving the equally intense cantilever beam into up and down bending periodically. The experimental result shows that the detection range for the reflected wavelength drift of FBG is 0～3 nm, the uncertainty of wavelength detection is 1 pm, and the uncertainty of the pressure measurement is 0.005 MPa when the measurement range of the pressure sensor is 0～6 MPa.