The invention discloses an ectopic and in-situ combined gravel bed water ecological-restoration system. The ectopic and in-situ combined gravel bed water ecological-restoration system adjusts measures to local conditions according to the surrounding specific situation of a riverway, adopts a riverway center position and surrounding position combined and gravel bed established water ecological-restoration mode and mainly comprises a surface-flow artificial wetland, an inflow water overflow dam, an in-situ gravel bed, an outflow water overflow dam, a flow guide overflow dam, a diversion canal, an ectopic gravel bed, an outflow water overflow weir and a water convergence weir. The ectopic and in-situ combined gravel bed water ecological-restoration system can effectively treat black and odorous riverway with a deteriorated water body and strengthen the purifying capacity of the water body itself, and enables the water body of the riverway to reach the surface water standard. In addition, the ectopic and in-situ combined gravel bed facilitates establishment of a complicated aquatic organism habitats, improves the diversity of the riverway habitats for animals and plants and strengthens the stability of a riverway ecosystem.