Reasonably anticipating and imagining future events or scenes improves individuals’ adaptability and promotes human’s survival and development. In recent years, researchers have investigated the cognitive processes and brain mechanisms of imagining the future, and proposed corresponding concepts and theories. We firstly summarized the widely used thought-sampling procedures and word-cuing paradigms, and then self-referential processing, mental scene construction and other cognitive processes were also elaborated. Moreover, we specifically introduced the default mode network and other-related large-scale brain networks, and proposed one brain network framework for imagining the future. Future research needs to comprehensively investigate dynamic and complex brain networks and their relationships with specific diseases.