Objective:To analyze and evaluate the degassing effect of vacuum degassing apparatus through the determination of ox-ygen content in pure water, gas pressure and air volume, and compare with suction filtration, boiling and ultrasonic methods to choose the appropriate degassing method for dissolution medium and guide the daily inspection work. Methods: The water residual oxygen, gas pressure and air volume were determined using a single water quality on-line monitoring instrument and a Carbo QC Anton Pear in-strument. The degassing effect of the vacuum degassing apparatus was detected under the conditions of negative pressure and certain de-gassing time. The degassing effect was also compared with that of suction filter, boiling and ultrasonic methods. Results: Under the conditions of 0. 06 MPa negative pressure, 41℃ medium temperature and 30 min degassing time, the degassing effect of the vacuum degassing apparatus was obvious. The degassing effect of suction filter and boiling methods was similar to that of the vacuum degassing apparatus, while that of ultrasonic method wasn't obvious. Conclusion:The use of vacuum degassing apparatus is simple and efficient with obvious degassing effect, which is suitable for the degassing process of dissolution medium.