Zr-in-rutile geo-thermometer has attracted wide attention and has been used in many cases.However,rutile temperatures derived from Zr-in-rutile thermometry in the Sulu-Dabie UHP eclogites were always lower than metamorphic peak temperatures calculated from other thermometers.In comparison with studies of domestics and overseas,and combining with the petrography observation,we considered that along with effect of the ultrahigh pressure on accommodation of Zr in rutile,retrogressive metamorphism and diffusion loss by fluid activity may be the most important factors that decrease the Zr content in rutiles.Significant differences of Zr content and temperature between different rutiles in an individual sample suggest that the high temperature equilibrium between rutile-zircon-quartz had been break off by the retrogressive metamorphism and could not gain re-equilibrium.Rutile temperature may represent some buffer state of each rutile grain after retrogressive metamorphism and diffusion to various extents;hence it is difficult to define geological meaning of average rutile temperature.Only in combination with occurrence of rutile,petrography observation and data homogeneity analysis,it is very likely to give an reasonable interpretation to the Zr-in-rutile geo-thermometer.