Polarized light-emitting device with a light source, multiple layers of first optical thin films and second optical thin films alternately stacked is disclosed. Each first optical thin film has a number of first geometric units, and each second optical thin film has a number of second geometric units. The first geometric units and the second geometric units are arranged as a secondary periodic structure on the light-emitting surface of the light source. The polarized light-emitting device is able to provide polarized light with higher brightness and polarized light of a specified polarization characteristic.