This paper analyzes the characteristics of development in small town, and it clarifies the connotation of sustainable development in the small town. At the same time, in it, small town is seen as a complicated system composed of society, economy, resources and environment, the relations among subsystems are also discussed. According to the connotation of sustainable development in small town and the relations among the four subsystems, the indexes can be divided into five: social index, economic index, resource index, environment index and the index of relations among subsystems, then the index system are established by the five kinds of indexes. Based on the index evolvement theory, this paper analyzes the progress of the small town, with the connotation of sustainable development, it presents an evaluation model of sustainable development in small town. Take advantage of this model, we appraise the small town of national sustainable development experiment - the sustainable development of the town of Hengdian, the evaluation results are in agreement with the actual development of Hengdian, which proves the index system and the model are scientifically.
