As a link between the city and the countryside, small towns play an important role in urbanization and realization of a moderately prosperous society. With human activity, climate change and notable contradiction between human and land,the pressure of drainage and flood control has become increasingly high for small towns in mountainous region. The problems and factors which affect the drainage and flood control were analyzed according to the characteristics of small towns in mountainous region. Combined with the types of small towns with different features of nature and humanities,the solutions and construction case for drainage and flood control in small towns were proposed in terms of constructing flood control project, building drainage system and pipeline network, focusing on vertical planning and promoting the construction of sponge city. The purpose is to provide reference for drainage and flood control planning and construction for small towns in mountainous region.