Objective To summarize the research development of spaceflight circadian rhythm of space chronobiology and to discuss the entrainment of circadian rhythm in apace flight. Literature resource and selection The professional reports, articles and books that published at home and abroad. Literature synthesis The system of circadian rhythm of space chronobiology is composed by receptors, pacemaker and effectors. The pace maker of mammals is located at suprachiasmatic nucleus and connected with receptors and effectors by neuron. Three neurotransmitters and one kind of hormone take part in the connection. And their secretions correlate with photic and some other nonphotic zeitgeber. Therefore under earth's light-dark environment, the cycles of the circadian rhythm is regulated to about 24 h. During spaceflight, the photic environment of spacecraft results in the endogenous rhythmicity change, and so does the phase and period of circadian rhythm. Conclusion Based on the rules and characteristics of photic and nonphotic zeitgeber of spacecraft, the entrainment of circadian rhythm is summarized.