The p ressure sensor characteristic of fiber Bragg grating is analyzed, the high－p ressure experiments about comp ression and decomp ression are carried out on the self－designing diaphragm, whose type is ZXYCO1,which fiber Bragg grating is stuck with the longitudinal and transverse methods. The experimental results indicate that the pressure sensitivity coefficient of fiber Bragg gratings in longitudinal stickup method is several times asmuch as that in transverse stickup method on self－designing diaphragm, their values are about 87 and 14pm /Mpa, theirmeasurement precision are 1% F. S and 0. 5% F. S respectively. At the same time there is a very good linearity and repetition between the centerwavelength of fiberBragg grating and p ressure change in two methods. There is rather high correlation coefficient, and it is fit for pressure measurement.