A fiber grating sensor including an elastic circular plate and one or two FBG'ss attached to the bottom surface of the elastic circular plate. Two ends of the FBG are connected to an optic fiber for signal transmission. The fiber grating sensor readouts are independent of temperature variation. The fiber grating sensor mechanism according to the present invention may be applied in a variety of sensors such as gauge pressure transducer, differential pressure transducer, load cell and displacement transducer with a distributive design, and for various purposes.