The hydraulic characteristic of ozone contactor has a great impact on the disinfection effect of microorganism. Computational fluid dynamics (CFD) technique was used to simulate the flow field of a single-column ozone contactor. The Eulerian multiphase model and the standard k-ε turbulent model were used in the simulation. The results show that ozone distribution is relatively uniform in the single-column contactor. In general, there does not exist the phenomenon of “dead zone”, which helps to guarantee high disinfection efficiency. However, gas bubble was found to accumulate underneath the outlet trough. The results offer a sample for optimizing the ozonation system.