Abstract: Catecholamine is one of the main functional components in tea, its effect is related to the molecularOrbit. From the calculation of Huckel’s molecular orbit(HMO), the seventh and eighth atoms in π-electronsystem possess string tendency of electron system, it affords sound theoretical basis for Belleau model.

Key words: Catecholamine； Hü, ckel&rsquo, s molecular orbit； &pi, -electron system； Free valence； &alpha, -accepter； &beta, -accepter；