Abstract: This is an article in the field of mining engineering. Coal gasification slag is a type of solid waste generated during the coal gasification process. The presence of residual carbon significantly limits its potential for reuse and recycling. Therefore, the extraction of residual carbon from coal gasification slag is a pressing concern. In this research, the separation of residual carbon and inorganic minerals from gasification fine slag was studied by hydrophobic-hydrophilic separation technology. The effects of stirring speed, stirring time, hydrophobic liquid dosage, pulp concentration, pulp temperature, and hydrophobic liquid type on the separation effect of carbon/ ash were investigated. The hydrophobic-hydrophilic separation technology has excellent carbon extraction and ash reduction effect on coal gasification slag, and the ash content of its carbon product can be up to 30% or less, while that of the ash product can be up to 95% or more. The separation mechanism was revealed by the characterisation analysis, which showed that the adsorption strength of residual carbon on paraffin was much higher than that of ash, which made the kerosene-treated residual carbon hydrophobicity greatly increased and easy to be captured by the oil phase. This study can provide important guidance for the efficient carbon extraction and ash reduction of coal gasification fine residue, which can help to achieve the comprehensive utilisation of coal gasification solid waste.