To describe the interaction of laser and medium accurately, the semi-classical vector theory for elliptical mode is presented. From the self-consistent field equations, the limitations of the circular vector theory are analyzed. Based on the elliptical mode eigenvector, the elliptical vector theory formula is derived and discussed. The discussion shows that, the elliptical vector theory is in accordance with actual physical mode and has specific physical meaning, which evolves into circular vector theory when ellipticity is zero and accords with the experiment results well part-quantitatively. It is helpful to improve the part-classical theory and ring laser.