In order to ensure water temperature of purification structure to meet the requirements of specification and prevent frost heave phenomenon, the paper put forward a technique method of purification water structures insulation that suitable for rural severe cold area. Taking Wafang village water supply station of Zhaoyuan County, Daqing City for example,the best method for purification structure and insulation materials insulation thickness was determined through combining the methods of theoretical calculation, simulation analysis with economic analysis. The results indicated the purification structure water temperature with 5cm thick polystyrene foam can absolutely satisfy the requirements and has good economics. Thus, the technical methods have broad applicability in the towns of severe cold area.