Abstract: Circadian rhythm is a phenomenon of diurnal changes in life activities formed by a transcription-translation feedback loop of biological clock genes affected by external environmental conditions. The circadian rhythm system controls almost all physiological processes in the organism, and these processes will change as the external environment changes. Previous studies have shown that the hypothalamic-pituitary-thyroid axis in mammals is regulated by the central diurnal pacemaker of the suprachiasmatic nucleus of the hypothalamus, so part of the thyroid function is controlled by the biological clock, and the secretion of thyroid hormones in blood can present a circadian rhythm. However, the molecular mechanism of the biological clock's regulatory effect on thyroid is still unclear. Whether circadian rhythm interference is related to the disorder of thyroid function or the occurrence of thyroid diseases is worthy of attention. This paper focused on the research progress of biological clock, circadian rhythm, and thyroid function, specifically the characteristics of circadian rhythm of thyroid physiological function and the effects of sleep deprivation, light at night, and night shift work on thyroid function, elaborated the relationships of circadian rhythm disorder with thyroid function and thyroid diseases represented by thyroid malignant tumors. The review summarized that circadian rhythm disorder may disrupt the rhythmic secretion of thyroid hormones, but no clear conclusion is reached yet on any effect on thyroid diseases, especially thyroid malignant tumors, so it is necessary to further strengthen the relevant epidemiological and molecular mechanism research.