Abstract: Elaborated in the essay are the modification principle and relevant calculation method for the shaper of the Φ508~1 422 mm HSAWpipe 2-step production line.All the parts of the equipment of the operation line as involving the steel plate width and pipe size are modified.And the problems as resulting from the expanding the lower limitation of the pipe size range are emphasized, and solutions are accordingly proposed.The analysis identifies that the operation line as modified with rather low investment is running well.The pipe size range lower limitation of the line has been expanded from the original Φ508 mm down to Φ406.4 mm, which means that the operation line has been capable of producing small-sized pipes, and this has been verified via actual production in commission.For the modification phase as follows, more costs shall be needed to reduce the diameter of No.1 and No.3 shaping rolls to 110 mm, reduce the roll stand size at the same time, and shorten the shaping roll distance to alleviate the roll impression sign.