In this paper, two fiber reinforced polymer/plastic (FRP) encapsulated fiber Bragg grating (FBG) sensors were installed on the two sides of the angle steel beam, which was used to measure the displacement and direction of the diagonal steel beam, so as to realize the health inspection of the angle steel structure. The sensors were respectively installed on the different positions of angle steel beam, and the relationship between displacement and strain transmission of angle steel beam was simulated by the finite element analysis. The optimum design of sensors installation were discussed and the experimental verification was carried out. The simulation and experimental rex sults show that the sensor has the capacity to discriminate the direction and measure the size of one side of the angle steel beam displacement when installed in a reasonable position. To realize the health monitoring by using optical fiber sensors on the structures composed by angle steel, such as bridges, electric towers and cranes, and so on, a basic research was provided.