Experiments have shown that,for the infiltration process in soils with sand interlayers,the changing of cumulative infiltration volume with time included two stages: an initial non-linear stage,and a gradually-formed linear,stable stage.Most current studies modeled the two stages separately based on the time that the linear,stable stage had been reached.This paper proposed a continuous approach by separating the initial,non-linear stage into two independent sub-processes.The first sub-process was for stable infiltration,and its rate equaled that in the second,stable stage.The second sub-process was a transient process for filling the storages in the upper layer soil,and its rate varied with lapsing time,which eventually diminished after entering the second stage.By incorporating this approach,the entire infiltration process could be fitted into a single model.Experiment proved that,not only could the model better describe the physical infiltration process,but also achieved better accuracy.