The random scattering effect of scattering medium on light is an important factor that restricts its optical focusing and imaging. The optical phase conjugation technique can realize optical focusing and imaging through the scattering medium by conjugate reduction of scattered light field, where the acquisition of scattered light field phase is the core of conjugate reduction. We expounded the basic principle of polarization phase shift, combined the polarization phase shift with the phase conjugation technique, and designed a novel digital optical phase conjugation system based on polarization phase shift. A 633 nm HeNe laser was used as the system light source, and frosted glass was used as the scattering medium to conduct scattered light focusing experiments.The experimental results show that the device can successfully achieve optical focusing through the scattering medium, and the ratio of the focal point to the background light intensity can reach about 400 times.