Regarding the problem of navigable water flow conditions within the intermediate channel of decentralized ladder locks，the present study delves into the impact of the intermediate channel section type on this aspect.A formulation for working head in the middle channel of rectangular section and trapezoidal section is proposed.Mathematical numerical simulation is used to study the influence of different section shapes on navigational flow conditions.The results show that:1) The working head of the intermediate channel filling and emptying water is consistent，and its water level shows periodic changes.2) Variations in section type have less effect on the flow trend and the time of water transfer at locks.3) Compared with the rectangular section，the intermediate channel with trapezoidal section can effectively reduce the water level variation，oscillatory wave height，maximum water surface slope drop，and maximum longitudinal flow velocity during the upstream lock discharge.This study provides theoretical support for the design of intermediate channels in decentralized ladder locks.