Fluid inclusions are fluid samples that were being entrapped in minerals, and their homogenization experiments are the very important experimental procedure and aspect for investigating the evolvement of rock- and ore-forming fluids. But fluid inclusions with high internal pressure, such as the CO2-rich fluid inclusions in pegmatitie of Jiajika deposit, western Sichuan, trend to decrepitation before total homogenization when heating in conventional heating stage at 1 atm. Therefore, we used hydrothermal diamond–anvil cell (HDAC) to heat CO2-rich fluid inclusions in quartz from No. 134 pegmatite dyke in Jiajika deposit under elevated pressure with pressure medium of H2O. The experimental results show homogenization temperatures of fluid inclusions decrease with the increase of elevated pressures, indicating that fluid inclusions are not isometrical exactly after entrapment. Therefore, to warn us that we should choose HDAC as the microthermometric testing tool in order to get more reliable and accurate data for fluid inclusions with high internal pressure which come from hypogenic ore deposits. Combining the homogenization results by using HDAC and Linkam THMSG600, we found that the homogenization temperatures and salinities of H2O-CO2-NaCl inclusions decrease when their homogenization stations change from liquid CO2 to the critical phase of CO2 and H2O, and to liquid H2O. These thermodynamic features indicate that spodumene crystallized earlier than quartz, and they entrapped crystal-rich inclusions and CO2-bearing fluid inclusions respectively. Because Li+ concentrates in the crystallization front of spodumene, the salinity of fluid inclusions in quartz decrease generally during the crystallization.