Most existing water hammer calculations in drainage pipe networks are based on the assumption of constant friction, neglecting the damping effect of dynamic friction on pressure fluctuations. To address this issue, a dynamic friction water hammer model was developed and solved using the method of characteristics. A water hammer test system was designed to verify the model, and the verified model was used to calculate and analyze an actual complex drainage pipe network with a pump group system. The results indicate that, compared with the conventional constant friction water hammer model, the dynamic friction water hammer model not only accurately simulates the first peak pressure but also precisely simulates the fluctuation peaks and periods of water hammer pressure throughout the entire transient process. For continuous and sustained water hammer events, the cumulative calculation error caused by neglecting dynamic friction cannot be ignored. The installation of air valves can reduce the maximum water hammer pressure by 22.7% and increase the maximum negative pressure in the pipeline by 73%.