Abstract: A large amount of acidic wastewater produced in the process of coal mining and after the closure of the pit has not been treated in time and effectively. Through the continuous discharge of the wellhead of the mining roadway, it has caused serious damage to the surrounding ecological environment. In order to effectively deal with the problem of acidic wastewater discharge from closed coal mine and reduce or eliminate the environmental damage caused by it, on the basis of summarizing the current technologies and methods of acidic wastewater treatment at home and abroad, focusing on the current situation and characteristics of acidic wastewater discharge from abandoned closed coal mine in Guizhou Province, according to the composition and content of toxic and harmful substances in acidic wastewater from coal mine, combined with the requirements of relevant norms and standards for the discharge standard limit of mine wastewater pollutants, a method for treating acidic wastewater from this kind of mine is put forward: that is, to set up a water retaining wall + roadway filling + closed wall in the roadway for the wellhead drainage of closed coal mine. Through the example verification, the mine No.1 wellhead is no longer drained, and the pH value in the mine No.2 water quality detection index is increased from 5.26 to 7.93, from acidic to weakly alkaline ; the total iron is decreased from 34.30 mg/L to 0.06 mg/L, and the total manganese is decreased from 4.34 mg/L to 0.05 mg/L; the total suspended solids, chemical oxygen demand（COD_Cr） and petroleum indexes don’t change significantly, and the effective treatment of acidic wastewater in closed coal mine is basically realized from the source.