The mechanic characteristic of reinforced slope is analyzed by considering the coupling between fluid and solid of foundation,and the mechanism of the coupling is illuminated by Biot consolidation theory.Then thevariety of lateral displacements,settlements in the soil and the strain of reinforcement are compared by numerical calculation considering the coupling or not.Outcomes from the calculation are compared with obtained data of a test road.The conclusion is that the outcomes which consider the coupling are more consistent with the real circumstance.So,the coupling between fluid and solid of foundation should be considered as much as possible when analyzing the mechanic characteristic of reinforced slope henceforth.This can be used to guide practical reinforced slope engineering.