To study the active constituents with agonistic activity on melatonin receptors,various chromatographic methods and preparative HPLC were used on fresh leaves of Camellia sinensis under an activity-guided isolation,affording nine compounds identified as (+)-7′,7′-dimethyl-5-hydroxy-2R,3S-trans-pubeschin (1),plumbocatechin A (2),(-)-catechin (3),catechin-3-O-gallate (4),gallocatechin-3-O-gallate (5),epigallocatechin-3-O-gallate (6),(-)-epicatechin (7),gallocatechin (8) and epigallocatechin (9).Among them,compounds 1 and 2 were obtained from the genus Camellia for the first time.Their agonistic activities were further evaluated by an MTT assay,and the result revealed the potential that compound 3 may be main active component of C. sinensis via regulation on melatonin receptors.