From a long time ago, there is a question to decide if a channel should be designed to have the highest hydraulic efficiency or the least cost.Channel cross-section design with an optimal cost under uniform-flow conditions includes minimizing the total cost per unit length of the channel. In this study, a large amount of construction cost of the channel was investigated and analyzed to calculate the cost function of the channel as a total cost associated with the land acquisition, channel material coverage and ground drilling depth for the channel. Case studies carried out in this technical note show that the difference between low-cost and efficient sections is closely related to the cost of the channel lining relative to the cost of land. When the base cover disappears to the unit cost of the land, the difference between the two parts is almost decreasing. This transaction was performed in the normal equation to provide a straightforward solution to the low-cost channel.