Collective future has been a subject of great concern in political science, communication science, sociology and other disciplines, but little is known about collective future thought in psychology -- that is, how individuals think about the future of a group. Individual future thought and collective future thought are separable and collective future thought can be studied as an independent field. The discussion of collective future thought is helpful to deepen the study of future psychological time and provide theoretical basis for the research of collective future. The paper aims to explain the concept of collective future thought, clarify the memory basis of collective future thought, and propose the possible direction of future researches. Firstly, the paper summarizes the concept of collective future thought, which literally means imagining a group event that has not yet happened. In this concept, imagination refers to the collective, imagined future events can be specific or schematic, and there are interactions between different groups. Like collective memory, collective future thought is a multiple and controversial process. The study of collective future thought is often based on collective memory. Therefore, to give a definition of collective future thought, starting from the perspective of collective memory is one of the methods. The two concepts related to collective memory, "future as after-thought" and "future as forethought", are used to define collective future thought. Meanwhile, these two concepts also constitute the complex interaction between collective memory and collective future thought in the collective context. Secondly, although no empirical study can directly prove the memory basis of collective future thought, it can be concluded from some related concepts and case analysis of patients with amnesia that the memory basis of collective future thought may related to semantic memory more closely. Firstly, previous studies have focused on episodic memory in individual mental time travel, while collective mental time travel is a psychological process involving more about semantic memory, so episodic memory has more influence on individual future thought, but semantic memory may play a greater role in collective future thought. Secondly, studies from neuropsychology and neuroimaging also prove that semantic memory is more closely related to collective future thought. Studies show that some amnesic patients have defects in episodic memory and episodic future thought, but their semantic memory is intact and they can imagine the future of the collective domain. Thirdly, hippocampus damage impairs the individual future thought, but the collective future thought ability remains intact, indicating that hippocampus doesn't play an important role in collective future thought. Meanwhile, non-hippocampal future scene construction exists and it may have an important relationship with collective future thought. There are many researches on the brain mechanism of collective future thought based on amnesic patients, but few researches on the brain mechanism of collective future thought in normal population. Finally, the paper puts forward the prospect of the future research of collective future thought. Firstly, more suitable experimental paradigms and measurement questionnaires should be developed. Secondly, future collective future thought should be based on Chinese culture. Finally, future studies can explore the brain mechanism of collective future thought in normal population.