Abstract: It is a common case that the strip steel deviates the centerline of the SWAH pipe mill during the operation. Based on relevant site test-running cases, the causes for the strip steel deviation from the centerline are investigated, and accordingly, countermeasures are proposed, such as adjusting the process parameters, optimizing reasonably the distance of flattening machine's down-pressure amount or the pressure of the delivery machine, and adjusting the strip parameter position, etc.