The flow patterns of a stilling basin with free discharge at the end sill of the basin downstream of a sluice are complex. Thus, the hydraulic characteristics and layout of the basin are significant to the engineering design and operation. Based on a hydraulic model test, the relationship between the stilling basin length and the end sill height was analyzed, and the layout method of the stilling basin is put forward: First, according to the Froude number in the inlet section of the stilling basin, the height of the end sill is preliminarily selected on the basis of the selected bottom elevation of the horizontal segment. Second, through adjustment of the end sill height and calculation of the water depth at the top of the end sill, the ratio of the sum of the two variables mentioned above to the water depth after the hydraulic jump is controlled within a range of 1. 15 to 1. 2, and then the ratio of the length of the horizontal segment of the stilling basin to the length of hydraulic jump can be reduced to within the range of 0. 8 to 0. 85. This method can reasonably determine the hydraulic and shape parameters of the stilling basin with free discharge at the end sill.