The invention provides an elbow type inlet passage with an arc-shaped spreader plate, and belongs to the technical field of water conservancy projects. The elbow type inlet passage comprises a linear gradually reducing section, an elbow gradually reducing section, a straight cone section and a separating pier, and is characterized in that the arc-shaped spreader plate is arranged in the elbow gradually reducing section, the longitudinal section of the arc-shaped spreader plate is in an arc shape, the central line of the arc-shaped spreader plate and the central line of the elbow gradually reducing section are consistent in shape. When water flow flows out of the linear gradually reducing section of the elbow type inlet passage, the water flow is uniform in flow speed distribution, but when the water flow flows in the elbow gradually reducing section, the mainstream of the water flow deviates to the inner side of the elbow type inlet passage and the flow speed of the inner side is higher than that of the outer side. Then, when the water flow passes through the elbow gradually reducing section of the arc-shaped spreader plate, the flowing and separating of the elbow gradually reducing section are reasonably controlled, the water flow of the inlet passage is more smooth in flowing, and the flow speed uniformity of the elbow gradually reducing section and the flow speed distribution of the outlet of the inlet passage are improved.