Abstract: This paper introduces the principle of improved shutdown process by using natural gas and its application on sulfur recovery unit. The process was improved from following aspects: (1) A mixture of natural gas and nitrogen for shutdown was used. The addition of nitrogen into the Claus furnace increased the amount of sulfur and heat-carrying gas during the shutdown period and shortened the downtime. (2) The air distribution during the shutdown process was determined through calculation to avoid over-temperature of the equipment and catalysts. The industrial application of Sinopec Beijing Yanshan Branch 60kt/a sulfur recovery unit showed that the flue gas SO₂ mass concentration emitted from the tail gas furnace during shutdown and blowing could be controlled within 100 mg/m³ without setting caustic washtower, which reached the discharge standard. The improved process has significant socialbenefits which can be further promoted and applied.