The Hamiltonian we used includes the static SSH model, the Hubbard model and Na+ phenomenological potential in trans-polyacetylene. When the distance of the soliton pair in Na-doped trans-polyacetylene is 15α, the effect of e-e interaction within an unrestricted Har-tree-Fock scheme on the band structure of trans-polyacetylene, the charge density of the chain and the half-length of the soliton are studied.