Abstract: Distributed temperature measurement optical fiber, about 10 km long, has been applied at the dam of Xiaowan hydropower project,which is so far the longest in China. This paper introduced temperature measurement optical fiber applied in conventional concrete construction. With no related technical standard in China, the paper summarized the experience of temperature measurement optical fiber rating and problems in construction. Temperature distribution graph of Xiaowan dam provides data for dam temperature controlling and can be reference for popularization and application of temperature measurement optical fiber.