The high-finesse optical microcavity is the core of a strongly coupled cavity quantum electrodynamics (QED) experimental system. However, due to the limited intervention space of an optical microcavity, it is difficult to obtain an effective initialization treatment to the atomic internal states trapped by the optical cavity. By selecting the light field that interacts with the ground state and a higher-order excited state of the atom, the limitation of the microcavity mirror on the intervention space is effectively avoided, and the optical pumping of the atomic internal states and the preparation of the atomic state (spin polarization) in the optical microcavity are realized. At the same time, based on the difference in coupling strength between optical microcavity and different internal states of atoms, a model for describing and optimizing the atomic polarization rate in the cavity is established and the state preparation efficiency of 85% of cesium atoms in the cavity is finally obtained.