Abstract: The process of resettlement in reservoir areas is a long one, involving a wide range of areas, and it is difficult to control investment. The problem of overestimating the investment in resettlement often occurs. Therefore, how to effectively control the investment in resettlement in reservoir areas has become an urgent problem to be studied. This paper analyzes the main factors affecting the reservoir resettlement investment from three aspects: external project environments, project subjects and project participants. It quantifies the comprehensive effect degree of the factors influencing the reservoir resettlement investment through DEMATEL-ISM model, and analyzes the hierarchical structure and overall impact relationship of different factors. The research shows that: There are 8 cause factors and 9 result factors among the 17 influencing factors of resettlement investment. ISM divides the set of influencing factors into 6 layers and 3 categories. Among them, land expropriation for construction and immigration scale, changes in physical quantity of immigration, implementation progress of resettlement, contract management and communication among project participants are direct influencing factors, while policy adjustment is an important influencing factor. Finally, according to the calculation results of the model, the authors put forward some suggestions: strengthening the fundamental influencing factors, paying attention to the intermediate influencing factors, and implementing the direct influencing factors, so as to provide a reference for the more accurate and effective control of the investment in reservoir resettlement.