The catenary residual voltage issue of DC traction power supply system is common in urban rail transit. This issue is a direct threat to the safety of the operators and maintenance personnel. It shows that the catenary is energized during the electrical inspection for power outages. This will lead to the failure of normal operation and maintenance, and the failure of the line test. This also affects the normal operation of substations. This paper takes Fuzhou Metro Line 2 as an example, which has the catenary residual voltage issue at the entrance and exit lines of Zhuqi parking lot. The causes of the catenary residual voltage issue were analyzed based upon the theoretical analysis and calculation, combined with the residual voltage test data collected from experiments. Furthermore, the measures to reduce the catenary residual voltage were proposed. The on-site test results demonstrated that the proposed measures can effectively suppressed the catenary residual voltage.