The high vacuum acquisition and vacuum maintenance of device-level vacuum packaging for MEMS gyroscopes are studied to increase their quality factors and stability. The relationship between error signals and quality factors is analyzed based on the dynamics equations of Z-axis MEMS gyroscopes and the air damping of gyroscopes with high quality factors is analyzed using rarefied gas dynamics theory.The changes of quality factor of an early vacuum packaged gyroscope are analyzed,and the result shows that residual gasses in vacuum cavity result in the decreasing of vacuum level.A temperature programmed desorption-mass spectrometry (TPD-MS) is used to measure the contents of the evolution gases for the ceramic packages and the lids.According to the contents of trapped gases,the reasonable getter is chosen to absorb the gases and to keep the vacuum level of the cavity.Finally,the device-level vacuum packaging process is improved.The test results show that the quality factor of the gyroscope packaged with a new device-level vacuum packaging process is about 162 660,which is about 14 times those of previous vacuum packaged MEMS gyroscopes,and the change of quality factor is less than 0.05% within one year.