Using the MSC.Marc software, the temperature and stress fields in beryllium during cutting process are studied by employing a thermo-mechanically coupled finite element method (FEM). The constitutive equation of beryllium is fitted with the Johnson-Cook plasticity model, and an user subroutine is written for modeling the chip separation after fracturing. The results show that the temperature in beryllium increases only a little and the highest temperature is about 45 ℃. Both of the residual stress components for parallel and vertical to the cutting direction are tensile on the surface of beryllium after cutting. The cutting force and thrust force are 280 and –250 N/mm, respectively, during the cutting steady state if the cutting process is adopted in this paper. This study is helpful to enhance the understanding for stress formation and the optimizing for the beryllium cutting process.