In this study, by mean`s of He`s Homotopy Perturbation Method (HPM) an approximate solution of Falkner-Skan equation obtained. In boundary layer theory, we have seen how similarity methods combine two independent variables into one, and therefore our problems our simplified to ODE Equations. If we use HPM we can deforms a difficult ordinary differential equation into a simple problem which can be easily solved. Comparison is made between the solution of Falkner Skan equation for 4 cases and those in open literature to verify accuracy of this work. Results show that the method is very effective and simple.