We suggest that the superconductors should be divided into two types, type A and type B, for the former, λΛ. The meaning of Λ is given in this paper. Our analysis shows that the influence of effective phonon spectrum on the transition temperature of these two type superconductors are different and the ways for raising their transition temperature are different also. For type A superconductors, the most effective way for raising Tc is to increase λ, whereas for type B superconductors, is to increase λ (ω2).