The physical phenomena and corresponding theoretical analysis of orthogonal polarized laser are reviewed. Four lasers (or systems) with orthogonal polarized beams are involved. For the birefringence dual frequency laser, its physical phenomena discussed include the alternation between strong mode competition and medium mode competition in cavity tuning; the range of frequency difference of strong mode competition (about 0-40 MHz); four polarization statuses (o-light oscillating but e-light extinguishing, both o-light and elight oscillating, e-light oscillating but o-light extinguishing, both o-light and e-light extinguishing) in cavity tuning; the tuning curves of frequency difference; the influence of optical activity of quartz crystal on polarization direction; and the aberrance of frequency splitting.For the Birefringence-Zeeman dual frequency laser, we focus on its intensity tuning and frequency difference tuning. For the feedback system of orthogonally polarized laser, we discuss the mutual suppression between two orthogonal frequencies, intensity exchange between two orthogonal frequencies and double of intensity fringe frequency. For orthogonally polarized LD-pumped Nd: YAG microchip laser, its property of the dependence of intensity sensitivity on frequency difference is described.