In view of the technical problem in structure selection of fishway groove neighboring the lock,we put forward the design technical route for the expansion of the fishway closely neighboring the lock in the existed navigation & hydropower complex.Based on the fishway expansion engineering of Dayuandu navigation & hydropower complex in the Xiangjiang River,the integrated structure which includes the fishway groove and lock is considered,and the fishway structure is arranged closely to the main structure of the second-line lock.The open-type U section or culvert-arch-type section for the fishway groove is selected according to the location of the fishway in the lock.By the scheme,we not only solve the problem of expanding the fishway in the existed navigation & hydropower complex,but also greatly reduce the land consumption and project investment.