On 21 February 2009, THEMIS-C satellite observed the classical signal of magnetic flux rope at magnetotail of X=-15.7RE.We take the method of Grad-Shafranov reconstruction to investigate the characteristics and structure of magnetotail flux rope. The results give the characteristic physics parameters such as the invariant axis direction, the cross scale length, the magnetic flux in flux rope, etc. With no constraint from model on shape of the flux rope, we reconstruct the distribution of magnetic field and electric current density in the cross section of magnetic flux rope at magnetotail. Our results show that the magnetic field in the central region of magnetic flux rope can be described as being force-free, while with the increase of radial distance, the fields display no force-free feature in the region where the magnetic fields deviate from the axial symmetric distribution.