Abstract: To disclose the transfer relationship of circadian rhythms of cellular messengers among central nuclei, the levels of cAMP and cGMP in cells of suprachiasmatic nucleus (SCN), dorsal raphe nucleus (DR) and pineal body (PN) in mice were measured at 04: 00, 08:00,12:00,16:00,20:00 and 24；00 for 2 days. The cosine parameters and equations for the circadian rhythms of cAMP, cGMP and cAMP/cGMP levels in SCN，DR and PN were derived respectively. The results showed that the peaks of circadian rhythms of cAMP/cGMP ratio in PN, SCN and DR appeared at 10： 23» 11： 05 and 11: 56， respectively, suggesting that the transfer sequence of circadian signal among the three central nuclei in mice was from PN to SCN, and then to DR.