A construction window forecast method of large-scale tunnel elements is presented based on the group decision-making algorithm. Based on superiority method and satisfaction value method, multi-attributes group decision making algorithm for force and stability condition screening and window forecast algorithm is also provided, optimal evaluation function decision-making method for selection of construction window is also provided, these methods can take a quick solution for environment limit conditions. The whole construction window forecast method is applied to construction window forecast for the undocking, floating transport and mooring of tunnel elements, the results show that the method can give a good suggestion for engineers.