The orientation parameter is used to describe the collision dynamic process and the structure informations of excited atomic state in electron scattering. In density matrix theory, the state multipoles express the structure of atom assembles impacted by particles, and the state multipole of K=1 expresses the orientation vector. In the sysmetry scattering plane system, the orientation vector is denoted by the orientation parameter L⊥, which is calculated from scattering amplititutes, C-G coefficient and 6-j symbol. The orientation parameters of sodium S→P excited by low energy electron are calculated in this paper, and the results are consistent with that obtained from electron-photon coincidence scattering experiment from 2eV—100eV incident energy. The characteristics of orientation angular-distribution vs incident energy are also discussed.