The invention discloses a fiber grating sensor capable of measuring temperature and pressure simultaneously and a measurement method. The sensor comprises a thin-walled cylinder with an opening at thebottom, and a protective shell enclosed outside the thin-walled cylinder, wherein a gap exists between the thin-walled cylinder and the protective shell; and a first fiber grating and a second fibergrating are fixed on the outer surface of the thin-walled cylinder, fiber pigtails of the first and second fiber gratings penetrate through the top of the protective shell, the cross section of the thin-walled cylinder is an elliptical shape defined by two straight edges and two semicircular arcs respectively connected to two ends of the two straight edges, the first fiber grating is fixed at thecenter of the surface of the straight edge of the thin-walled cylinder along the axis direction of the thin-walled cylinder, the second fiber grating is fixed at the center of the surface of the semicircular arc of the thin-walled cylinder along the axis direction of the thin-walled cylinder, and the centers of the first and second fiber gratings are at the same height as the center of the thin-walled cylinder. The sensor disclosed by the invention has the characteristics of novel structure, high sensitivity, reliable measurement result, and wide application.