The invention provides a sulfur tail gas purification process for direct discharge after treatment. On the basis of a conventional Super-SCOT process, the absorption pressure inside an absorbing tower is 0.05-0.25MPa; the absorption grade inside the absorbing tower is not smaller than that of an actual tower plate of 18 layers; a desulfuration solvent for deamination comprises the following components in percentage by weight: 20-50% of N-methyldiethanolamine (MDEA), 0-30% of diisopropanolamine (DIPA), 10-50% of sulfolane, 1-2% of a protonation agent and the balance of water; a semi lean solution is sucked out from 1-5 layers above a middle layer in the middle of a regeneration tower and is moved upwards along with increase of the content of CO2 in a deamination raw material gas; two semi lean solution inlets are longitudinally formed in the middle of the absorbing tower; when the content of the CO2 in the deamination raw material gas is higher than 10% (mol/mol), the semi lean solution is fed into the feeding hole above, or else the semi lean solution is fed into a feeding hole below; COS is hydrolyzed into H2S and CO2 by using a fine desulfurization process, H2S is adsorbed and reacts to generate sulfide, and a treated purified gas can be directly discharged. The purified gas treated by using the method can be directly discharged without incineration, and thus relatively low sulfur discharge standards can be met with relatively low energy consumption.