Migmatites, such as pegmatite and granitic leucosome are widely distributed within biotitebearing orthogneiss in the Weihai area, north Sulu ultrahighpressure (UHP) metamorphic terrane, eastern China. A combined study of mineral inclusions, cathodoluminescence (CL) images, UPb SHRIMP dates, and insitu trace element and LuHf isotope data for zircons provided insight into the nature and timing of partial melting in these rocks. Most magmatic zircons in the studied pegmatite sample WH19 have distinct overgrowths around inherited magmatic cores (type I) or occur as new, simple crystals without inherited magmatic cores (type II). Inherited magmatic core with Qtz + Kfs + Pl + Ap inclusions, record 206Pb/238U ages ranging from 769 to 228 Ma, which show a upper intercept at 788±20 Ma and a lower intercept at 228±20 Ma, representing a Neoproterozoic protolith age and a UHP metamorphic age of biotitebearing orthogneiss as a host rock, respectively. In contrast, newly formed magmatic zircon core and mantle with Qtz + Kfs + Ap inclusions that record partial melting time of 219.5±1.4 Ma shortly after UHP metamorphic age, whereas the magmatic rims record a younger (214.6±1.7 Ma) Late Triassic regional amphibolitefacies overprint. These data indicate that the partial melting in the north Sulu UHP terrane took place in the UHP biotitebearing orthogneiss, but that occurred during postUHP, retrograde granulitefacies metamorphism. Furthermore, crystallization of the magmatic zircon associated with the partial melting was complete by the time of the regional amphibolitefacies retrograde stage. Inherited magmatic zircon cores from pegmatite sample WH19 give disperse 176Lu/177Hf (0.00031~0.00360) and 176Hf/177Hf(t) (0.282051~0.282348) with εHf(t) ratios of -8.3~2.1 and Hf model ages (TDM2) of 1.43~2.02 Ga, indicating the protolith of the biotitebearing orthogneiss as the host rock was generated by reworking of Paleoproterozoic crust. In contrast, the newly formed magmatic zircon cores and mantles have Hf isotope (176Lu/177Hf = 0.00031~0.00099; 176Hf/177Hf = 0.282175~0.282225; εHf(t) = -16.7~-14.9; TDM2 = 1.91~2.0 Ga) distinct from those of the inherited magmatic zircon cores. These relationship support our conclusion that the early magmatic zircon (cores and mantles) crystallized by dissolutionreprecipitation of preexisting inherited magmatic zircon in an open system during granulitefacies retrograde stage. Compared with the newly magmatic zircon core and mantle, the magmatic zircon rims have older model ages (TDM2 = 2.03~2.21 Ga), and lower 176Hf/177Hf (0.282110~0.282168) and εHf(t) (-20.6~-17.3), and disperse 176Lu/177Hf (0.00059~0.00288), indicating that these late magmatic zircon (rims) also crystallized in an open system during the late regional amphibolitefacies retrograde stage.