An improved homotopy analysis method with two auxiliary parameters was introduced, then the homotopy approximate solutions for the generalized KuramotoSivashinsky equation were obtained by using this method. which were compared with the exact solitary wave solutions. And the comparison shows that the approximate solution more effectively approaches the real solution, because it contains two auxiliary parameters, which can regulate and control more effectively its convergence region and rate. This indicates that the improved homotopy analysis method with two auxiliary parameters has its advantages to study complex nonlinear systems.