Abstract: The performance of the filter elements configured at the gas station and the user entrance changes dynamically with the service conditions. If the filter element is not cleaned and replaced in time, the gas passing efficiency will be affected seriously, resulting in the sharp increasing of local resistance and great drop of throughput, and thus endangering the safety of gas supply. Based on the investigation and analysis of the working conditions of gas filters in urban gas engineering, a numerical model of gas filter was established, and the flow field inside the filter was simulated with the CFD software. The results show that the change of inlet speed has a great influence on the filtration effect under the condition that the inlet pressure is remained unchanged, and the blockage of filter element at different locations has different impact on the passing of gas flow. Therefore, regular cleaning, maintenance and replacement of filter elements are very important to keep the filtration efficiency. In the case of limited conditions, it is recommended to give priority to the replacement of the lower filter elements. Generally, the research results could provide reference for further simulation research on the actual working conditions.