The cross sections of the ls electron photoionization and corresponding shake-up processes for Li atoms in the ground state 1s22s and excited states 1s22p, 1s23s, 1s23p and 1s23d are calculated using the multi-configuration Dirae-Fock method. The latest experimental photoelectron spectrum at hv = 100eV [Cubaynes D et al. Phys.Rev. Lett. 99 (2007) 213004] has been reproduced by the present theoretical investigation excellently. The relative intensity of the shake-up satellites shows that the effects of correlation and relaxation become more important for the higher excited states of the lithium atom, which are explained very weI1 by the spatial overlap of the initial and final state wavefunctions. In addition, strong dependence of the cross section on the atomic orbitals of the valence electrons are found, especially near the threshold.