In order to improve the accuracy of fiber Bragg grating (FBG) pressure sensor and decrease the cost of the whole system,a measuring method of using the fiber Bragg dual-grating to measure the pressure is proposed in this paper. Under the action of external pressure,the reflected wavelength drift of the sensing FBG is transformed into time interval variation of light pulse reflected by a scanning 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 detecting 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.