The utility model discloses a catalytic liquefied petroleum gas deep sweetening device. In an extraction unit, alkali liquor of mercaptan in the catalytic liquefied petroleum gas is extracted, and the catalytic liquefied petroleum gas to be treated passes primary fiber liquid membrane equipment, secondary fiber liquid membrane equipment and tertiary fiber liquid membrane equipment, and is finally delivered out of the device through washing treatment; and in an alkali liquor oxidation regeneration unit, sodium mercaptide in the extracted alkali liquor is oxidized into sodium hydroxide and disulphide in the existence of catalyst and oxygen, the disulphide in the regenerated alkali liquor is subjected to primary separation, and the disulphide in the regenerated alkali liquor is extracted in a solvent by adopting a process flow of two-stages of fiber liquid membrane equipment and counterflow of the solvent and the regenerated alkali liquor, so that the disulphide in the regenerated alkali liquor is separated. The catalytic liquefied petroleum gas deep sweetening device has high removal rate to low-molecular-weight mercaptan and high-molecular-weight mercaptan in the catalytic liquefied petroleum gas, and has the advantages of high disulphide separation efficiency, low alkali consumption, less waste alkali emission and the like.