Carbon/P-zeolite composites (CPZCs) were synthesized by high-temperature activation followed by hydrothermal crystallization using waste coal gasification fine slag as the raw material and NaOH as the activator. Methylene blue was selected as a dye pollutant for the adsorption experiment to investigate the adsorption property of the carbon/ P-zeolite composites. It was found that the structure of CPZCs mainly depended on the mass ratio of NaOH to the coal gasification slag. At a proper NaOH to the coal gasification fine slag mass ratio of 1.0, the as-synthesized CPZC- 1.0 exhibited a typical Na-P zeolite structure with a relatively high specific surface area of 200m2/g and pore volume of 0.21 cm3/g. CPZC-1.0 showed excellent performance on methylene blue adsorption, with the adsorption capacity reaching 130mg/g with removal efficiency of 81.6% at 303 K for the 100mg/L initial methylene blue solution. The calculation results of adsorption thermodynamics indicated that the adsorption process to methylene blue by CPZCs was a spontaneous and entropy-driven endothermic process. Based on the above research, it is speculated that the adsorption mechanism of CPZCs to methylene blue might be due to the van der Waals force, intermolecular hydrogen bond and electrostatic attraction between Na-P zeolite and methylene blue.