The hospital ward was sterilized by using gas ClO2 as a bactericide, and the air and surface of the ward were sampled by plum sampling method, inoculated by plate coating method, and colony count. The conditions of different ClO2 concentration, sterilization time and sterilization time were investigated. The killing effect on the pathogenic microorganisms on the air and surface of the ward. The results show that under the premise of human activities, the optimal conditions for sterilizing the hospital ward are: gas ClO2 concentration 0.3mg/m3, sterilization time 60min, sterilization time Section 20:00~21:00 (under fluorescent light), the sterilization rate of air can reach 99.8%, and the sterilization rate of the surface can reach 93.9%.