Abstract: Based on the current domestic level of controlling diameter accuracy of the HF welded pipe,elements as affecting the diameter and ovality of such pipe are analyzed.Taking the actual production circumstances of the Φ244.48 mm×8.94 mm J55 ERW pipe into consideration,effects by the sizing roll pass and its repair parameters on the diameter and ovality of the said welded pipe are mainly analyzed.As a result,it is regarded that proper control of wearingof thesizingroll groovewill getthepipediameter accuracy ensured,and theout-of-toleranceovality eliminated.