According to the working condition of super long spacing in the first stage construction project of Xiaomiaohong waterway extension project in Nantong Port，we analyze the the hydraulic characteristics of the ship and pipeline，such as the pressure head of mud pump，transmission resistance loss and etc，verify that the “2 pumps + 2 pumps” series construction technology adopted by the “Xinhaijiao” and “Hangjiaojie No.1” can ensure the construction demand of the super long spacing，and deduce the optimal construction position of “Hangjiaojie No.1”，which can solve the problem that the local discharge pressure is too high after the multi-stage mud pump series connection. We apply the results of process calculation and optimization measures to the follow-up engineering practice. The results show that the optimization improves the hourly interest rate and production rate of ship group，and achieves good construction effect.