The application of CaF2 crystal in photolithographic machine becomes a hot research topic. However, differentdefects in the crystal seriously restrict its actual performance. In this paper, the morphological and spatial extension characteristics of etch pits formed by the crystal face (111) of CaF2 crystal were observed, and the corresponding defect characteristics of various etch pits were analyzed, which is aprerequisite for the accurate characterization and control of crystal defects. The results show that the etch pits on the crystal face (111) of CaF2 have three types, i.e.,triangular conical pit, cone-flat bottom pit and flat bottom pit. Triangular conical pits and cone-flat bottom pits have directional movement characteristics, indicating that the corresponding defects of these pits are related to the dislocations of the materials. However, there is no spatial extension in the flat bottom pit, which is formed after the defects are completely corroded, and the corresponding defects may be the remains of local defects such as impurities, vacancies and small dislocation rings. The physical parameters of the formation process of the etch pit are obtained, and the kinematic model of the etch pit is establishedby tracking the evolution process of the etch pit in real time. This work provides a basis for further studiesonthe corrosion theory of crystal materials.