Abstract: The creep rupture test results of ferritic/austenitic dissimilar metal welds by nickel base alloy, austenitic and ferritic fillers show that the mismatch of creep strength between different materials is the main cause of premature failure of dissimilar metal welds during elevated temperature service.In order to compromise the big difference of creep strength between ferritic steel and austenitic steel, a spool with medium creep strength may be added and joined between them. Thus the creep rupture strength (life) of the dissimilar metal welds can be raised to the same level of that of the ferritic similar metal welds.