The utility model discloses a deep purification system for natural gas desulfuration and decarburization. The deep purification system comprises a cyclone separator, a gravity separator, an absorption tower, a flash evaporation device, a lean-rich liquid heat exchanger, a regeneration tower, a regeneration tower overhead condenser, a regeneration tower overhead return tank and the like which are connected in sequence. The deep purification system has the advantages of being capable of performing conventional purification of sulfur-containing raw natural gas and deeply removing H2S, CO2, sulfur alcohol, COS and other organic sulfur impurities in the raw natural gas in one time, meeting the purification index requirement of common commercial natural gas, and meeting the gas quality index requirement of liquefied natural gas (LNG) to raw natural gas.