Drainage channels with step-pool configurations, one type of debris-flow drainage system used in gullies with steep gradients, have good application potential because of their high-performance control effect and engineering value. In this study, a pool depth design method is proposed based on the hydraulic jump theory. The dynamic behavior of debris flows in drainage channels with step-pool configurations is explored via a series of specially made flume experiments, where the debris-flow bulk density and the scale and depth of the step-pool configuration are the main controlling factors. The debris-flow pattern and flow depth are investigated along with the material-interchange phenomenon. There is a dramatic difference in the dynamic behaviors of different types of debris flows. Because of the associated intense turbulence and particle collision, the observed material-interchange phenomenon was greatest when the debris flow with a bulk density of 1700 kg/m(3) passed through the drainage channel. The analysis indicated that, when a debris flow passes through a step-pool configuration, the flow depth increases significantly as a result of the hydraulic jump. However, a step-pool configuration with an overly large depth traps sediment, which is detrimental to transporting sediment. In addition, modified coefficients of the proposed design method were determined based on an analysis of the experimental results. The analysis further indicated that the coefficients significantly depend on the debris-flow viscosity and turbulence. Our results can be used to improve understanding of step-pool configurations and provide a reference for practical engineering design.