Abstract: Based on the microscopic sdIBM-F_max model and the single-particle energies from experiment, with the use of the most general Hamiltonian, the vibrational band and rotational band in 108Cd nucleus as well as its evolutional process were reproduced very well by two different groups of nucleon-nucleon effective interaction parameters. And phenomenological study identifies that: 1) The coexisting region of two excitation models is on the interval between the state 8⁺₁ and state 14⁺₁ (this is a interval with E_x=3.683-5.503 MeV), and the 8⁺₁ state is a state preponderant in the vibrational model, the 14⁺₁ state is one predominant in the rotational model, while the state 10⁺₁ is a cross-bencher state relative to the two models; 2) The yrast states from the ground-state up to the 24⁺₁ state all are collective states, hereafter the first breaking up and aligning state maybe is a two-quasiparticle state of neutron on the intruder orbits h_11/2; 3) This structure evolution has been achieved via the moderate changes of the pair coupling probability of valence nucleons in the coexisting region, and thus is not very rapidly.