Abstract: During the operation of vacuum system in high-flux laser device, molecular contamination generated by the pump lubricating oil in the vacuum environment may diffuse and deposit on the surface of optical system components, induce damage under high-flux laser irradiation, and reduce the devices’ load capacity. Research has been conducted on the cleanliness control of vacuum systems, and a series of technical measures have been developed to control the vacuum system cleanliness, including optimizing the vacuum pump group, increasing low-temperature cold trap adsorption, and adding online heating regeneration technology for the cold trap. The experimental research results show that after 120 h of continuous operation, the average surface deposition of non-volatile residues in the vacuum system reaches a clean level of 2.86 × 10⁻⁹ g/cm² after 24 h; The transmittance at 350 nm and the damage density curve below 12.3 J/cm² flux of the fused quartz optical test piece assessment group and control group are basically consistent, proving the effectiveness of this method.