Abstract: In the spiral welded pipe manufacturing process,the strip longitudinal edge pre-bending operation step is very critical for preventing and controlling occurrence of the so-called “spade” shaped defect of the pipe forming seam.Described here in the article is the method for pass design for a 2-roll edge pre-bending apparatus.Thanks to this method,the calculation formula for the edge buckling of the strip in the forming process is obtained,and relevant mathematic model is set up for the 1/ρ,i.e.,the pre-bending curvature(the neutral layer)of the strip edge in the said pre-bending apparatus.As a result,the design for roll profile of the 2-roll edge pre-bending apparatus,and the bending setting of the 3-roll edge pre-bending apparatus will be properly directed.The job is also helpful in guiding activities for improvement on quality of the spiral welded pipe forming seam,and actual operations as well.