Abstract: Light-wall steel tubes are widely used in many fields.A common problem as encountered with in manufacturing of such tubes is bulging of the material during formation process.The root cause of this undesirable phenomenon is that the extension of the strip edge area is out of the elasticity limit of the material.In the paper the cause for the said bulging is analyzed with the deformation theory.Also proposed are certain solutions for the problem,involving the material,process arrangement and roll groove design,etc.