In this article, COD, volatile phenol and ammonia nitrogen concentrations of the wastewater from semicarbon are reported as 38,000; 6,400 and 5,700 mg/L, respectively. According to the field test, when the pH of the wastewater is 9, the field test temperature is 20 °C, the adsorption time is 30 min and the optimal dosing ratio of nitrogen-doped gasification slag (HX-NGS) to the wastewater is 1:4, HX-NGS has the best removal effect on COD, volatile phenol and ammonia nitrogen in the wastewater from the semicarbon. The removal rates of COD, volatile phenol and ammonia nitrogen are 94, 91 and 85%, respectively, and the concentrations of the remaining COD, volatile phenol and ammonia nitrogen are 2,280, 576 and 855 mg/L, respectively, after regeneration, the material HX-NGS has a good effect on the treatment of the wastewater from the semicarbon. The reuse rate of the adsorption material is at least eight times. The adsorption effect of the material HX-NGS conforms to the mechanism law of dynamics and thermodynamics.