Abstract: It is an important way to promote the high-quality development of new-type urbanization in China through improving the urban design quality and shaping the style and characteristics of small towns. Different from large-scale cities, the small towns is suitable for walking scale, production and living space are closely related, and the morphological evolution of road network is closely combined with spatial development. It is an important content to promote the renewal of urban design technology in China to construct a spatial analysis method adapted to the spatial characteristics of small towns. As an improved version of space syntax, sDNA has the characteristics of strong pertinence, compatibility and stability, and easy operation. Based on line segment analysis of sDNA, this paper explores the practical effect of space syntax in urban design of small towns through an empirical study on urban design of Guli New town in Jiangning District, Nanjing City, Jiangsu Province. Finally, the limitations of space syntax in urban design are discussed based on the review of research progress at home and abroad, and the future application direction of space syntax is discussed by constructing sDNA-based urban design technology for small towns.