Five different wall functions were used to simulate the intake manifold of muti-cylinder gasoline engine by CFD method, and the uniformity of intake mass was analyzed. The computed and analyzed results show that the two layer models wall functions are more accurate than the standard wall function; the non-equilibrium wall function is not suitable for the analysis of uniformity of intake mass because of its worst calculation precision; among the three two layer models wall functions (Wolfstein model, Norris & Reynolds model and Hassid & Poreh model), the Hassid & Poreh model has the maximum mean intake mass and the smallest no-uniformity.  