This paper has demonstrated the structural strain measurement of the steel beam with the distributed fiber optical sensor system based on Brillouin scattering. The experiments were conducted both in the lab and in outdoor conditions. When it is in outdoor environment, the temperature compensation must be taken into account for the sunlight radiation effects. The compressive strain can be measured without need of the pre-tension on the fiber. The spatial resolution of the strain measurement is 0.5 m. The strain measurement accuracy is 10 (mu) (epsilon) for the lab environment.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.