This paper studies the transmission characteristics of continuous fluctuation in pipelines based on the water hammer equation in reference to the circuit impedance analysis method. The influence of external pipelines on wave transmission was analyzed, and a filter was designed for fluctuation in pipelines at a certain frequency. Finally, the relationships among pipe length, filter size and wave transmission were explained. Practical applications show that this filter designed on the basis of the impedance theory can effectively restrain the fluctuation of pumping pressure and improve the accuracy and efficiency of the pressure test.