We generalize Yamadas perturbation theory and develop a renormalized perturbation method to study the asymmetric Anderson model. We obtain the occupancy of the local electrons,the renormalization factor,the renormalized energy level,and the renormalized parameters,which are expanded by the bare parameters. We also calculate the density of states of local electrons and the conductance of impurity scattering. The results coveres the range from weak to strong coupling. We find that the approach we adopted is more convenient than Hewsons renormalization method in studying the asymmetric Anderson model.