Magnetic geopolymer (Fe3O4-CGGP) was prepared from coal gangue, and evaluated by Fenton-like degradation of phenol. It was found that Fe3O4 with a particle size of 10-20 nm was uniformly dispersed on the surface of coal gangue geopolymer (CGGP). The saturation magnetization of Fe3O4-CGGP reached 35.68 emu/g. These indicated that Fe3O4-CGGP had a good catalytic activity and magnetic responsiveness. The effects of pH value, catalyst dosage, H2O2 dosage, and initial phenol concentration were investigated on Fenton-like degradation of phenol. The optimum conditions were as follows: pH is 3.5, catalyst dosage 0.5 g/L, and H2O2 10 mmol/L. Under the parameters, phenol can be completely degraded in 60 min. The free radical quenching experiment revealed that ·OH dominates the catalytic process in the Fe3O4-CGGP/H2O2 system.