Abstract: This is an article in the field of environmental engineering. In this article, the composition, structural characteristics and surface properties of coal gasification crude slag (CGCS) and coal gasification fine slag (CGFS) were characterized by X-ray fluorescence analyzer, scanning electron microscopy, FTIR spectroscopy, specific surface area and pore size analysis, and the results showed that CGFS had a more developed pore size structure and larger specific surface area. The adsorption test results show that the adsorption of n-butyl sodium xanthate by the two coal gasification slags is consistent with the Langmuir adsorption isotherm model and is a spontaneous heat process, which conforms to the quasi-secondary kinetic model, and the adsorption rate constant CGFS > CGCS. Among them, the adsorption performance of CGFS to n-butyl sodium xantho can reach 181.95 mg/g due to CGCS.