Abstract: The temperature and stress fields in beryllium ring are analyzed by ADINA/ADINAT software during electron beam welding.The result shows that the highest temperature at the outer surface reaches 2 734 ℃, while the highest temperature at the inner surface is only 378 ℃, which is located at the side of out opening of beryllium ring. After welding, residual stress is considerable large and complexity within 2.0 mm from the weld line and residual stress reaches the largest at the weld toe. For the structure difference between in opening and out opening beryllium ring, residual stress at the in opening beryllium ring is not as same as that at the out opening beryllium ring.