The aim of this investigation was to develop an environmentally friendly nano-hydraulic turbine utilizing extreme low head waterfall. The relative distance between a runner and a waterfall is one of the important factors for stable generation. It is often necessary to adjust precisely the relative position every time flow rate change, because that flow rate always change. So, changing the runner position or controlling the waterfall direction is needed. But the former is very difficult from the viewpoint of generation cost. We, therefore, focused on the flow direction control method via a curved channel. Open cross-flow runner was selected, and the runner performance was evaluated for several types of curved channel. As a result, turbine performance has the biggest impact on fast water velocity made by small radius of curvature.