Seasonal reproduction is a common life history strategy evolved by mammals inhabiting in temperate and arctic zones. This physiological process is controlled by hypothalamic-pituitary-gonadal axis (HPGA). As a circadian pacemaker, the suprachiasmatic nucleus (SCN) could oscillate spontaneously and respond light entrainment, then trigger rhythmic changes of melatonin, hypothalamic thyroid hormone, Kisspeptin as well as RFamide-related peptide (RFRP) to regulate the annual cycle from anestrus to reproduction. This review summarized the current understanding on annual clock and photosensitive neuronal circuits for regulating seasonal reproduction, and emphasized the significance of circadian clock, thyroid hormone, Kisspeptin, and RFRP.