The comparative experiment was conducted to compare the effect of ch and air along with gamma rayon the disinfection efficiencies against Salmonella choleraesuis, E. Coli K12 and Staphylococcus aureus. The microorganism for the disinfection experiments were prepared by transferring the bacterial stock culture into 50 ml nutrient broth and incubating for 24 hrs at 37℃. The initial concentration of the harvested culture was approximately from 10^(7) to 10^(9) CFU/ml. One set of the culture solution was the control without any gas purging. The other culture solution was purged with high-purity(99.99%) O2 and air for 30 min just before irradiation, and was sealed with the screw caps to keep O2 and air concentration in the solution. The culture solution in 15 ml tube screw cap bottles without a headspace was irradiated at different absorbed doses of 0.1, 0.2, 0.3, 0.4. 0.5, 0.7, and 1kGy. The disinfection efficiencies of O2 and air saturation with gamma radiation of 0.2kGy ag외nst Salmonella choleraesuis, E. Coli K12 and taphylococcus aureus were 94.54, 99.94%, 96.31%, 76.51%, 93.4% and 86.66%, while only gamma radiation was 89.93%, 75.48% and 75.5% % at 0.2kGy. Therefore, O2 purging or aeration with radiation technology such as e-beam has promise as an effective process for the disinfection of the municipal wastewater treatment effluent.