Abstract: IMPACT OF FILLET WELD ON FATIGUE STRENGTH OF PRESSURE VESSEL SIX IMPORTANT ISSUES IN STRESS ANALYSIS OF PRESSURE VESSEL （Ⅵ） [1] Guo Xuehua , Wang Xiaomin , Xia Shaoqing , Yan Dongsheng （ SINOPEC Engineering Incorporation ,Beijing , 100101） Abstract ： Obvious stress concentration exists on the fillet weld between shell and its external attachment pad of the pressure vessel subjected to cyclic loading. It is not convenient to machine and implement comprehensive non-destructive examination for this kind of fillet weld, so fillet weld has great impact on the fatigue strength of vessels.Design standards of many foreign countries regard the impact on fatigue strength as a fatigue strength reduction factor.However,designers in our country often ignore this important factor influencing fatigue strength during fatigue analysis of pressure vessel.