The investigation results of laser polarization, mode competition and phenomena by their combination are summarized. These findings are obtained with cavity tuning of orthogonally polarized dual frequency lasers including He-Ne lasers (birefringence He-Ne laser, birefringence-Zeeman He-Ne laser), microchip NdYAG lasers and vertical cavity surface-emitting lasers (VCSEL). 28 most important physical phenomena, instead of all, are presented, which describe characteristics comprehensively in this kind laser and will benefit the laser science and applications.