Aiming at the research of nondestructive and non-contact measurement based on optical coherence,the method of designing and constructing common optical path laser shear interference system is proposed using Wollaston prism (WP) as the shear component.In this paper,the effects of its components on the imaging quality of interference fringes are analyzed in detail,and a series of conditions to obtain the optimal interference fringe are acquired.Subsequently,the convective vortex cell structure and temperature distribution of the fluid in the transparent square cavity under the action of temperature gradient are obtained by using the constructed system,which preliminarily verifies the feasibility of the system in this research field.On the basis of the above research,combined with image processing and iterative algorithm technology,the system has a great application prospect in three-dimension field reconstruction.