This study was divided into two parts. Firstly, according to the infinite slope analysis method and considering the influence of seepage force, the critical state of debris flow was conducted. Secondly, the water flume model test was performed to examine the suitability of the critical state of debris flow at Linkou Terrace. The experimental results show that the critical state of debris flow conducted previously is in good agreement with the experimental observations, which can explain that the samples fail because the driving force along the failure plane is larger than the shear strength of soils. The critical state of debris flow may appear more exactly when considering the effect of surface erosion.