Taking the coupling between the quadrupole and octupole interaction into account, the splitting of two-phonon octupole states in 208Pb and quadrupole moment Q(3-) are studied by using the generator coordinate method (GCM) and the Holstein-Primakoff boson expansion method (1940). The authors find that the energy splitting is small and depends more sensitively on the multipole force strength chi lambda ( lambda =2,3) than the quadrupole moment Q(3-).