The experiment for four kinds of synthetic rubber materials outgassing rates property was performed on the vacuum material outgassing rate apparatus.The constant volume method was adopted for the experiment study.The results show that the four kinds of synthetic rubber materials outgassing rates is 10-7 Pa·m3·s-1·cm-2 at a total pressure of 10-3 Pa during four hours.Additionally,the outgassing rates decreases with increasing pump-down time.Many mass spectrums in mass peak from m/z=70 to m/z=200 were observed during this test using H200M quadrupole mass spectrometer.It means that the synthetic rubber materials release some macromolecule matter.