The dimensional change, residual stress, grain orientation difference, dislocation density, and dislocation distribution of beryllium after different hot isostatic pressing treatments were analyzed by laser length meter, Raman spectrometer, nanoindentation meter, electron backscattered diffractometer, and transmission electron microscope, and the influence of thermal-cold cycling treatment on the dimensional stability of beryllium was analyzed. Results show that the size of the hot isostatic pressed beryllium tends to be stable after 6 cycles of thermal-cold cycling treatment from -100 °C to 150 °C, and it has good dimensional stability. The dimensional stabilization mechanism of beryllium is mainly the homogenization of dislocations within the grain and the homogenization of orientation difference caused by micro-plastic deformation.