A method to eliminating the stress delay from fiber grating pressure sensors by means of dual fiber grating is proposed. The tuning for Bragg wavelength disparity of the dual grating can be realized in the case of the effect of external pressure by a method that symmetrically adheres two FBGs with the same wavelength respectively to the upper and down surfaces of the cantilever beam and links them up in series.The result of the research shows that the technology can eliminate the stress delay of the fiber-grating pressure sensor caused by the elastic material of the devices,and improve the linear response characteristic and repeatability. Under the condition of the pressure range of 0～40 MPa,the tuning range of the system dual-peak wavelength disparity is 5.12 nm (two times of the range of single-peak wavelength tuning) and the sensitivity of dual-peak wavelength disparity in pressure tuning can reach the high degree of 0.128 nm/MPa (also two times of the single-peak one.