Mercury and its chemical compounds are highly toxic. During the maintenance and cleaning process of mercury-containing gas field equipment, the diffusion of mercury and its compounds can cause environmental pollution, seriously threatening the occupational health of maintenance personnel. The cleaning and protection against mercury in such equipment remains a significant technical challenge both domestically and internationally, with no mature experiences to draw from. Taking the green maintenance of equipment in KS mercury-containing gas field as a case study, an innovative method for cleaning mercury-contaminated vessels was developed, the maintenance process was optimized, and new devices for environmental and human protection against mercury exposure were created. This resulted in a comprehensive green maintenance and cleaning technology for mercury-containing gas field equipment. Applying this technology has considerably reduced the cleaning time, enhanced the cleaning effectiveness, and substantially lowered the concentration of mercury in the environment. Site practices have shown that this technology holds economic, safety and social benefits, providing technical support for the green, safe, and efficient maintenance of equipment in mercury-containing gas field.