Abstract: The analytic expression of the intensity of any polarizing direction versus the phase difference in polarization coherent beam combining is deduced. The validity of the expression is proved by experiment. The coherent beam combining(CBC) experiment based on polarization phase discrimination is designed to verify the feasibility of CBC based on polarization phase discrimination. The phase of two laser beam is locked using gradient descent algorithm and a stable power output is acquired. The advantage of this technology and the requirement of lasers are analyzed. A scalable architecture of full aperture CBC based on polarization phase discrimination which can be proportionally amplified is proposed. The quick degradation of the bandwidth of the stochastic parallel gradient descent algorithm(SPGD) as the increase of the CBS beams is solved by multiple parallel phase detection and modulation.