Abstract: Disclosed are a step-by-step paired and up-down reciprocating combined fishway and a fish passage method thereof, belonging to the technical field of fish passage facilities. The present disclosure aims to provide an efficient fish passage technology for a low-head water control project, which overcomes the defects of long construction length and low fish passage efficiency of the traditional fishway. The present disclosure includes several fishway units, a mechanical transmission system, a fish repelling system, a control system, and a recovery cableway. Under the combined action of the mechanical transmission system and the fish repelling system, the fishway units reciprocate up and down step by step to form a fish passage way. The weight of the fishway units is balanced through the rotation of coaxial eccentric wheels, and the energy consumption of the mechanical transmission system is reduced.