Carbon contamination in a synchrotron radiation (SR) beamline is a significant factor affecting the transmission efficiency in the beamline, particularly in a soft X-ray beamline. Currently, the main solution to carbon contamination is to clean or replace the contaminated optical components. A large number of experimental studies have shown that the formation of carbon contamination is related to the presence of a small amount of oil on the chamber wall. Therefore, the purpose of this study was to clean the vacuum chamber wall of the mirror box and obtain a cleaner vacuum chamber by glow discharge, striving to fundamentally prevent the formation of carbon contamination. This paper applied the Glow Discharge Cleaning (GDC) system to the Shanghai Synchrotron Radiation Facility (SSRF) beamline mirror chamber. The volt-ampere characteristics of the device under different vacuum pressures were studied. Mass spectrometry was then performed to analyze the residual gas in the mirror chamber before and after the glow discharge as well as the GDC process. The result shows that the primary cracking products of residual oil molecules in the vacuum chamber were mainly particles with molecular weight of 69. After being cleaned by glow discharge, the quantity of oil molecules (molecular weight 39, 41, 43, 55, 57, 69, 71) can be reduced by 50%, proving that glow discharge has a remarkable effect on removing oil molecules from the surface of the mirror chamber in the beamline. The GDC system is of great significance to reduce carbon contamination, especially in soft X-ray beamlines.