Based the three dimensional scales transformation of E.M.theory,the analytical expression of scattering field from a conductor elliptic cylinder is presented,as the electromagnetic wave propagating vertical to the axis of an elliptic cylinder with arbitrary incident angle and polarization.The obtained result is in agreement with that in the reference when we use the analytical expression to calculate the scattering field from a cylinder.The varying of scattering width of this elliptic cylinder with the incident azimuth angle,frequency and sizes of the target is simulated.It is shown that the vertical size of the elliptic cylinder effects greatly the scattering field when we observe it in the direction perpendicular to the direction of incident wave.The scattering field is strong as the polarization direction of incident wave parallels to the axis of the elliptic cylinder.The algorithm used in the article can be able used to investigate the scattering characteristic of other elliptic cylinders.The obtained result offers a theoretical foundation for the practical applications such as electromagnetic remote sensing of target′s size and shape.