Hydraulic experiments on installing a permeable spur dike at three positions (1/4, 1/2, and 3/4) at the concave bank of the bend of a spillway chute with three angles (45°,60°and 75°) were carried out for studying the backwater condition in front of the permeable spur dike. Results show that the maximum backwater height occurs at the cross-section where the permeable spur dike meets the concave bank of the bend. A formula of the maximum backwater height was derived by the employment of the principle of momentum conservation, and the formula indicates that the height is influenced by the geometric parameters of the permeable spur dike and the bend, the layout of the spur dike in a bend, and the inflow discharge. Based on experimental data, a regression analysis was implemented on the water depth coefficient in the formula. Furthermore, the maximum backwater height can be obtained through the water depth at the concave bank of the end of bend when the parameters and installing pattern of the permeable spur dike were determined.