The invention relates to a system device for pipeline natural gas in steel plate cutting and application, and belongs to the field of mechanical manufacture. The pipeline natural gas for cutting is prepared by adding a TD rare earth nano polymerizing agent into natural gas as master batch and adding oxygen for adjusting a flame to be blue-white, wherein the inner flame is 5-8 mm in length. According to the system device, the flame temperature can reach 3,400-3,600 DEG C, the pipeline natural gas can be continuously supplied, a steel plate cutting hole is smooth and flat, has few molten slags and can be very easily cleaned, the cutting quality of a workpiece is guaranteed, the production cost is greatly reduced, and the production efficiency is greatly improved.