There is a pile of rock blocks which contain corundum+spinel+garnet+fibrolite association in the form of lenticular enclaves in khondalite series along the Day Nui Con Voi, northwestern Vietnam. The mineral association is resulted from ultrahigh-temperature metamorphism. The coexistence of spinel and quartz indicates that the metamorphic temperature is higher than 900℃. Meanwhile, the biotite-garnet thermometer and biotite-plagioclase-garnet-quartz association thermobarometer for the mineral associations during retrogressive metamorphism gave temperature and pressure ranges of 879~917℃ and 0.90~0.94GPa, respectively. The early stage metamorphism is featured by the occurrence of corundum+fibrolite assemblage, which marks a shift of metamorphic conditions from upper amphibolite facies to granulite facies. Meanwhile, the peak metamorphism is characterized by the spinel+quartz assemblage, which indicates an ultrahigh-temperature metamorphic condition (temperature higher than 900℃). On the other hand, the formation of ilmenite during retrogressive metamorphism suggests that the rocks experienced a drastic decrease in pressure after the peak metamorphic conditions. The metamorphic P-T path shows that there is an early coeval increase in temperature and pressure and a subsequent rapid increase in temperature before reaching the peak conditions. In addition, a fast isothermal decrease in pressure characterizes temperature and pressure evolution after the peak metamorphism. Such a P-T path is in accordance with the temperature and pressure evolution of anomalously heated slab due to upwelling the asthenosphere by the break-off of subducting oceanic plate during plate convergence. SIMS U-Pb dating of zircons from the ultrahigh-temperature metamorphic rocks gave a minimum age of 58Ma. Therefore, it is suggested that the ultrahigh-temperature metamorphism along the Day Nui Con Voi is related to the convergence between the Indian and the Eurasian plates.