Abstract: Here we report the discovery of coesite in phengite eclogite at Sanqinge, Ganyu county, Sulu UHP terrane, east China. These eclogites coexist with the UHP magnesite-bearing marble. The coesite relics and polycrystalline quartz after coesite are observed within garnet grains with radial fractures. This finding indicates that the Sanqinge phengite eclogites underwent metamorphism at pressure of >2.8 GPa. Metamorphic pressure for the mineral assemblages of cores correspond to 3.1~3.5 GPa ( T＝650~689℃ ) and their rim assemblages correspond to 2.9~3.3 GPa ( T＝652~671℃ ) by using garnet-omphacite Fe2+-Mg geothermometer and phengite baromemter.Quartz exsolution and sulfide exsolution textures occur in omphacites and apatites, respectively. Apatite contains abundant volatiles such as OH, F, Cl, and S, and its subduction to deep mantle is of great significance for the cycle of these volatiles. Based on our approximate estimation, the mass of OH, F and Cl subducted into deep mantle via Sulu-Dabie subduction zone was in the order of 80 000 Mt.