Abstract: The three-row hydrogenation tail gas treatment unit of Suining Longwangmiao Purification Plant, which belongs to Chongqing Natural Gas Purification Plant General of PetroChina Southwest Oil & Gasfield Company, was built and put into operation successfully. After more than half a year's trial operation, it passed the performance evaluation smoothly. Combining with the trial operation stage and current production status of the unit, the optimal process control parameters of the tail gas treatment unit were summarized, analyzed and optimized as follows: the mass ratio of fuel gas to low pressure steam in the online combustion furnace was 1:2, the hydrogen volume fraction in the quench tower outlet was 0.5%-2%, the pH value of acid water at the quench tower outlet was 6.5-7.5, the inlet temperature of the reactor was 210-230 ℃, and the absorber inlet temperature of the feed gas was lower of 1-2 ℃ than that of the lean liquid. The top temperature of the regenerator was about 110 ℃. The suggestions and measures were put forward to ensure the safe and stable operation of the hydrogenation tail gas treatment unit in Longwangmiao Purification Plant.