Abstract: A study on pressure calibration of a triaxial testing apparatus with solid confining media is presented with temperature up to 625℃ and confining pressure up to 6.5kb. The solid confining media used were Pb,AgCl and Nacl. For room temperature, phase-transition materials, such as NH₄I, phenol, AgI, NH₄F and KNO₂ were used to establish the relationship between the pressure applied on the specimen and the nominal pressurre measured outside The vessel. The correction of confining pressure △σ_c changing inversly with temperature was determined quantitatively by the "temperatueeffect" tests. It is shown that the pressure transmitting behavior of NaCl is obviously improved above 200℃ and a semi-emperical expression for △σ_c was derived for NaCl as a function of temperature T(℃), i. e. △σ_c = (0.491 + 0.000650T) [2.325-0.455 (T-25)^0.217].