Abstract: Comparative analyses are made with the performances for the X80 seamless and the straight-seam welded steel elbows. As a result it is concluded that the chemical compositions，the metallographic structures and the girth weld properties of the two are basically the same；compared with the straight-seam elbow，the ductile-brittle transition temperature of the X80 seamless hot-bent elbow is below -60 ℃，and its low-temperature toughness is relatively better，and has uniform overall distribution，smaller fluctuation range，better pressure-bearing capacity，and higher bursting safety factor than the straight-seam elbow；in general，all the performance indexes of the X80 seamless hot-bent elbow has been up to or even better than applicable DEC technical terms and the requirements under related specification.