Using Jordan-Winger transformation and finite Fourier transformation, the Hamiltonian of XX chain can be transformed to the diagonal form. If the total qubits number N=odd, the internal energy U, and correlation function G_zz in thermal equilibrium can be calculated. Then the pairwise concurrence and the critical value β_cr can be calculated. For N≥5 XX chains, there are pairwise concurrences in thermal equilibrium for antiferromagnetic and ferromagnetic cases when β>β_cr.