Abstract: Cell-to-cell mapping method was used for the study of the planar passive walking models with straight legs and kneed legs. Fixed points can be obtained by the period cells, and the periodical gaits can be determined. This method can avoid the randomness of the initial values when choosing of the iteration. The basins of attraction of our models are larger than the point foot model, and periodical walking can begin from points that far from the fixed point. The effects of parameters variation on the basin of attraction are discussed and some parameter combinations are determined which can have large basins of attraction.