In the technology of optical surface measurement, the phase-shifting shear interferometer had been widely used. In measurement, the phase-shifting was introduced in time domain, and the measurement system adopted double optical path for change phase-shifting and shear, so the measurement accuracy was limited. To decrease error, a commonpath phase-shifting shear system based on birefringent optical devices was introduced. In this system, the lateral shear and phase-shifting 0, π/2, π, 3π/2 was introduced in the commonpath optical system. Because the birefringent optical devices can introduce shear in the collinear optical system, a new Jones matrix was established. Based on the Jones matrix theory, the principle theory was analyzed in detail. In the experiment, an optical surface was measured with this system. The theoretical analysis and experiment results demonstrate the feasibility of this approach.