In this study, tunnel-structured cryptomelane was synthesized by a reflux method, and its crystal structure, crystal cell parameters, particle morphology and specific surface area were characterized. The degradation activity of cryptomelane on phenol with or without light was evaluated. In addition, the effect of pH and mineral loads on degradation of phenol were also investigated. The results indicated that a small amount of phenol was degraded by cryptomelane without irradiation, but a large amount of phenol was degraded under irradiation. The decrease of pH, the proper mineral loads and the concentration of phenol can all promote the degradation of phenol.