Precision desulphurisation of waste rubber powder by twin-screw melt extrusion using a thiol compound A /lauric acid compound desulphurising agent was applied. The effect of the compound desulphurising agent on the desulphurisation effect of the desulphurised rubber was investigated by permeation gel chromatography, scanning electron microscopy, differential scanning calorimetry and infrared spectroscopy. The results show that the optimum desulphurisation process of the compound desulphurising agent is to use 10% softening component (furfural extraction oil), 5% desulphurisation component (thiol compound A) and 5% promotion component (lauric acid) to carry out the precise desulphurisation of the waste rubber powder at a desulphurisation temperature of 220 ℃. The solubility content of the desulphurised specimens can reach 70.1% with a relative molecular weight of 13105. The sulfhydryl group in thiol compound A can precisely act on the C-S, S-S and multi-S bonds and break them, and lauric acid can promote the desulphurisation reaction through lubrication.