Abstract: For water delivery systems with special channel arrangements such as single pipe,single machine,and multi-node surge chambers,surge chambers are usually set up to meet the requirements of regulating and ensuring the calculation of large fluctuation control values and stable operation of small fluctuations.Due to the mutual flow of water in the large well of the surge chamber,hydraulic connections between the units are inevitable.In order to deeply study the hydraulic interference phenomenon in this kind of hydropower system,based on the data of the expansion project of a power station,and the method of characteristics of the pressurized water delivery system,a multi-node surge chamber model was introduced to analyze the impact amplitude of hydraulic interference according to different surge chamber locations,different regulation modes and other factors.At the same time,the transient process simulation calculation was carried out for the two typical hydraulic interference conditions of single unit load rejection and single unit startup load increase,and the unit output and surge chamber water level fluctuation data were obtained.According to the unit output fluctuation at different surge chamber positions,the impact amplitude of hydraulic interference was analyzed,and the measures to improve the regulation quality of units in the hydraulic interference transient process were proposed,which provided a reference for similar hydropower systems.