Abstract: In the analysis of the ultimate bearing capacity of foundation, the base width plays a very important role. In a general formula of a centrally and vertically loaded strip base, Nc and Nq have accurate values which are not affected by the base width; while Nγ does not have a true uniform solution. Therefore, the effect of base width on bearing capacity is converted to that on Nγ. Based on the Mohr-Coulomb theory, the effect of B on Nγ of γ-c-φ soil with different surface roughnesses and different dilation angles is analyzed by the elasto-plastic finite element method. Excellent agreement is obtained by the comparison among the finite element method and the classical limit equilibrium methods, limit analyses, multi-block upper bound method. The results show that the base width has more remarkable effect on Nγ under smooth base than that under rough base. The effect is much more remarkable when the non-associated flow rule is considered, particularly with the little dilation angle.