Coal gasification slag is a kind of solid waste in the field of coal chemical industry,the large amount of coal gasifi-cation slag discharge causes great pressure on the natural environment so it is particularly important to resource-based utiliza-tion of it.Based on the special structure and large specific surface area of coal gasification slag,the influence of coal gasifica-tion slag on the adsorption performance of phosphate under different adsorption conditions was studied,and the desorption and re-adsorption characteristics of coal gasification slag on phosphate were also researched.Results showed that the adsorp-tion of phosphate by coal gasification slag conforms to the Langmuir isothermal adsorption model and the pseudo-second-order kinetic reaction model.Under the adsorption conditions,such as pH of 7,feed amount of 2.5 g/L,temperature of 30 ℃ and time of 480 min,the saturated adsorption amount of Langmuir reached 3.998 4 mg/g.In addition,the coal gasification slag also has better desorption efficiency and re-adsorption capacity for phosphate.The study results showed that the coal gasification slag has the potential to be used as a sustained release agent for phosphate fertilizer.