Although zircon ages of 1800~1900 Ma have been reported from khondalite in Huangtuyao and adjacent areas, there has still been a debate on the time of the khondalite (Archean vs. early Proterozoic) because zircon of khondalite dates the peak metamorphism rather than sedimentation. On the basis of the content variation of HfO2 and ZrO2 from core to edge in zircon, most of elliptical and round zircons studied in the paper are determined to be metamorphogenic. However , some zircon overgrowths contain a square core with {110} cleavage traces, suggesting that they are remaining magmatogenic zircon. Becuase the protolith of khondalite is sedimentary rocks, the magmatogenic zircon represents ferrigenous detrital material. The information on two age groups is shown by plotting the data of single-zircon fractions on a U-Pb concordia diagram. Taking the aspect of two age groups and Pb-loss into account, it is able to draw more than two discordant lines. The ages given by three upper intercepts with concordia are 1873, 2169 and 2310 Ma, respectively. The first corresponds to the formation age of zircon overgrowth, i. e. the age of peak metamorphism. The second is a mixed age of metamorphogenic zircon with the detrital core. The last corresponds to the age of the detrital zircon, i. e. the age of sedimentation of the khondalite. In addition, metamorphic rutile from the same sample yields a high-precision U-Pb age of 1793 Ma, corresponding to the cooling age of the Huangtuyao high-grade terrain.