This study was carried out to evaluate the performance of three kinds of single process (electrolysis, UV and ultrasonic process) for the purpose of disinfection of Escherichia coli in water. Among the five kinds of electrode material, disinfection performance of Ir electrode was higher than that of the other electrodes. The order of disinfection performance for E. coli in single process lies in: electrolysis > UV $gg$ ultrasonic process. Performance of the three single processes was increased with the increase of the electric power. Disinfection efficiency of the three processes was increased with the decrease of the pH. Disinfection of the UV process were decreased by the increase of NaCl dosage and air flow rate. However, ultrasonic process was not affected above two parameters. OH radical was not produced in UV and ultrasonic process. E. coli disinfection of the electrolysis process was well agreed with RNO degradation tendency, except pH.