The laser output characteristics under elliptically polarized optical feedback effect are studied.Elliptically polarized light is generated by wave plate placed in the feedback cavity.By analyzing the amplitude and phase of the laser output in the orthogonal direction,some new phenomena are firstly discovered and explained theoretically.Elliptically polarized feedback light is amplified in the gain medium in the resonator,and the direction perpendicular to the original polarization direction is easiest to oscillate.The laser intensity variation in amplitude and phase are related to the amplified mode and the anisotropy of exteal cavity.The theoretical analysis and experimental results agree well.Because the output characteristic of the laser has a relationship with the anisotropy of the exteal cavity,the phenomenon also provides a method for measuring birefringence.