UV-written fiber Bragg gratings is adopted to study its strain sensing properties. Axial strain and refractive index changes of fiber gratings are caused by external strains so that Bragg reflected wavelength is shifted. The strain of fiber gratings vs. Bragg reflected wavelength is measured experimentally at 20℃ using spectrum analyzer that can disperse in the region of 400～1800nm wavelength and using InGaAsP/InP light emitting diode as bandwidth source. It shows that Bragg reflected wavelength shift vs. external strain changes of fiber gratings is linear in the range of 155.4～156.8nm wavelength.The sensitivity of fiber grating to the external strains is 1.211pm/με

which basically agrees with theoretical calculation. By the using strain sensing properties of fiber grating

the sensing head of pressure has been designed and made. It consists of a upper and a below metal plates and two fine adjustable screws on the upper metal plate. Two ends of fiber gratings are fixed respectively on two fixed points. The microrise and microdrop of the upper metal plate which acts as load stage can be regulated by fine adjusting screws. By adjusting the screws in stretch strain region of the fiber gratings

the fiber grating becomes as long as possible to keep larger linear region of the sensing head. And tested zero of the sensing head is determined at constant temperature of 20℃. The shift of Bragg reflected wavelength caused by pressure changes are measured with sensing head under two same material plates with different thicks. It shows that different gauge regions can be designed by chosing metal plates with different material or same material metal plates with different thicks. The sensing head of pressure can be widely applied in the measurement of different gauge regions and loads.