Abstract: Due to the advantage of high strength and light weight，prestressed concrete structure has been widely used in large-span civilian and military constructions． The control of prestressing construction is the key to ensure the safety of the structure． Therefore，an accurate and stable monitoring is an important measure for ensuring its construction quality． In the meanwhile，the long-term health monitoring for the working state of the structure is also needed． The technology of fiber bragg grating ( FBG) has been proved effectively for the monitoring the tension of prestressed structures． In this paper，FBG was applied to the monitoring of prestressing tension during the construction of a large theater． The result showed that FBG technology could completely record the change in strain during the construction and the data was stable and reliable． Furthermore，which provided a sensing platform for longterm health monitoring of a structure．