Structural health monitoring is a method of collecting information about the condition of structures, so that the structure can be used in a reliable and accurate manner. With such information about the condition of the structure, the initial failures can be anticipated to be overcome. This method includes a wide range of techniques based on fiber optic sensors to prevent failures and implement a maintenance system in face of them. Structural deterioration over time is inevitable; furthermore, because of different physical loads applied to the structure, the growth of cracks and fractures in the structures, make engineering structures, such as bridges, buildings, tunnels, dams, airplanes, ships, etc., need to take care and repair. Structural health monitoring systems are the most important tools to assess and ensure the health of the different buildings. In recent years, much research has been applied to the design and development of structural health monitoring systems to identify the damage of civil and mechanical structures. With the rapid advancement of science in the field of photonics and optics, a new sample of fiber optic sensors was considered. Fiber Bragg grating sensors are examples of this important achievement. Based on alternating refractive index of the core of an optical fiber, which changes due to ultraviolet radiation, the gratings are built. The structural health monitoring system are one of the important fields of fiber Bragg gratings applications. The application of this type of fiber is to determine some parameters, such as vibration, temperature, and pressure in the structural components. Using this technology, will allow instantaneously investigation of vulnerable structures such as bridges, dams and buildings, which are vulnerable, and damage survey and monitoring of their components is difficult. In this thesis, with the help of mathematical equations analysis to the study of fiber Bragg grating sensors, in some variety of approaches on structural health monitoring is desired. Sensing process, using fiber Bragg gratings, in structural health monitoring of bridges, as the selected structure, is simulated and the factors affecting these systems are also examined. Keywords: fiber Bragg grating, fiber optical sensors, structural health monitoring, Bragg wavelength.