A dual polarization laser is studied based on the Faraday magneto optic effect of TSAG and the polarization characteristics of Nd∶YVO4. When there is no magnetic field,the laser has only a single polarization output. When the magnetic field is applied,it becomes dual polarization output,and the polarization angle and power of laser vary with the magnetic field intensity. With the increase of magnetic field intensity,one output power is decreasing,while another one is increasing. Dual polarization laser can be used in displacement measurement,regional environmental monitoring,dual comb ranging and other fields.