As for tailor welded pipes in the pressurization and propellant feed system of carrier rockets, design and development of a flexible auxiliary system for precise location during the welding assembling of pipes are conducted, aiming to realize the flexible assembling during the welding of tailor welded pipes. According to the traditional manufacturing mode of tailor welded pipes, the welding assembling is based on the special welding fixture to guarantee the manufacturing accuracy of space dimensions, thus a special welding fixture is needed for each pipe. The adjusting or improving of pipe structures will lead to the repairing or even abandon of the existing fixture, causing a high production cost and long production cycle, and this problem is especially obvious in the developing carrier rockets. With increasing of the type of carrier rockets, the amount of the special welding fixture will increase obviously, bringing with a great challenging of the management of special welding fixtures. A flexible auxiliary system for precise location during the welding assembling of pipes is designed and developed to realize precise moving and locating according to the concrete assembling requirements, setting the feature point coordinates of pipe as the control command. Finally, a flexible assembling system can be suitable for the welding assembling of pipes with different space dimensions.