This paper presents a method of spatial shape rebuilding and target positioning for a robot used in searching and rescuing lives in ruins. In order to rebuild a spatial curve representing the shape of the robot body which is 3.5 m long, a long curvature sensor is designed based on fiber Bragg grating (FBG) to detect spatial curvature information, and the spatial curve fitting is realized based on these discrete spatial curvatures. After shape rebuilding, this paper realizes searching and rescuing target positioning using a threeaxis electronic compass to detect posture of the datum point of shape rebuilding. Experimental data show that the targeting error is about 10 cm which basically meets the target positioning requirements of robots. With the posture detection of a threeaxis electronic compass, the shape and position detection system becomes more effective and practical.