By solving the effective mass equations using the difference method, taking into account the strain effects and valence band mixing effect, we have compared the band structures, DOS′s of valence band and the optical matrix elements for different shaped wells. With the same well width, rectangular well has the strongest confinement on carriers, but parabolic and triangular wells have flatter DOS curves, which are more analogous to step like DOS. Thus laser diode and semiconductor laser amplifier with these two kinds of wells as active layers may have lower transparent current densities. The mixing between valence subbands has greatly changed the optical matrix element, so it will have influence on the gain characteristics of quantum wells.