Calcium fluoride (CaF2) crystals have high UV transmittance (>99%@193 nm) and high resistance to laser damage threshold, which have been widely used in the fields of high-power UV lasers and ArF laser lithography stepper. Stress birefringence is the key performance index of calcium fluoride in practical application, stress birefringence can cause deformation of the optical wavefront, which seriously affects image quality. Calcium fluoride crystals 210 mm in diameter were prepared by Bridgman-Stodebarger(B-S) method. The effects of crystal dislocation and small angle grain boundaries and crystal quality on stress birefringence were systematically studied. The experimental results show that the increase of dislocation density, the aggregation of small angle grain boundaries and the deterioration of crystal quality can cause the concentration of local residual stress and exacerbate the phenomenon of stress birefringence.