This study carried out UPb SHRIMP dating on the metamorphic zircons and metamorphic compound zircons from the gneissic alkaline granite, Moshan, Donghai. Eight points on the metamorphic zircons and metamorphic compound zircons have been tested, and yielded an weighed average 206Pb/238U age of 212±3.6 Ma（MSWD=7.55）. This indicates that the metamorphic time of the Moshan gneissic alkaline granite, i.e. the age of the diagenesis, belongs to late Triassic (Indochina epoch). The old cores of the metamorphic compound zircons (inherited zircon) are magmatic clastic ones in which rhythmic circles were developed. Dating on three zircons yielded UPb age of 866 Ma, 378 Ma and 370 Ma, respectively, implying that they the zircons are allochthonous and polygenetic and protolith of host rock should be probably sedimentary rock, formation of which should be later than Late Paleozoic.