Abstract: The pressure and composition of the residual gas in the microcavity are very important for the vacuum packaging devices.In the study,an analysis technology of the residual gas pressure and composition in the microcavity is proposed,and a test platform is developed.The platform is based on the ultrahigh vacuum dynamic conductance method,which can be applied to the residual gas pressure and composition in a small volume of less than 1 mL.In the experiment,the residual gas pressure and composition in 470 μL chips were tested.The residual gas pressure of chip 1 and chip 2 were 629.8 Pa and 646.8 Pa respectively.Chip 3 optimized the packaging process.After aging,the internal residual gas pressure decreased by one order of magnitude,about 31.9 Pa.The quadrupole mass spectrometer has been used to monitor the gas pressure in real time.CH₄,N₂and CO were the main gases in the chip aging process.