Due to the uneven distribution of flow velocity when the water flows in the middle section of the bidirectional flow guide device, affect the power generation efficiency of the horizontal axis turbine. By studying the blade radius and installation position of the turbine inside the guide device, improve the power generation efficiency of the turbine inside the two-way guide device in the two-way water flow. First, using Fluent to obtain the flow velocity distribution curve of the vertical section of the center of the diversion device. By means of numerical analysis, established the mathematical model of velocity distribution, and calculated the optimal blade radius. Then, by studying the variation law of flow velocity distribution in the vertical direction, obtained the optimal blade installation position. Finally, through the drag experiment, obtained the periodic power generation under the bidirectional water flow. The research results show that when the blade radius is within the linear range of the flow velocity distribution, the flow velocity of the rotating surface of the turbine blade is larger, and the flow velocity of the rotating surface of the turbine blade increases significantly as the blade installation position decreases. When the water flow velocity is 1 m/s, after adjusting the blade radius and installation position of the turbine, the power generation of the turbine is increased by 72% compared with the previous one, and the power generation by the bare blade is increased by 150%.