Based on three- dimensional digital image correlation (3D- DIC) method, the three- dimensional shape of dental impression is measured by mosaic techology. Due to the surface feature of the dental impression is complex, a four camera system is utilized for the measurement. The system is made up of two groups of 3D- DIC subsystems. The local profile is measured by each subsystem and the global morphology is acquired by mosaicking each local profile. Compared with the result of traditional two cameras 3D- DIC method, the proposed method gains a better 3D profile of the complex dental impression, which provides a new way to measure the 3D profile of dental impression, and it also provides reference to the 3D profile measurement of complex surface.