The invention relates to a manufacturing method of a steel rotational moulding pipeline with modified polypropylene inner liner, which comprises the steps of: welding, sandblasting, heating and heat preservation, rotational moulding, cooling, negative pressure test, positive pressure test, detection of an inner liner and the like; the modified polypropylene inner liner inside the pipeline manufactured according to the invention has the prominent characteristics of good compactness, high mechanical properties, strong integrity, no joint and welding seam, even thickness, high / low temperature and negative pressure resistance, strong adhesive force, corrosive resistance, impact resistance, no toxicity, convenient maintenance, etc. The steel rotational moulding pipeline, as an ideal material for taking the place of rubber, glass steel and stainless steel, is quite stable for a long time in various strongly corrosive media such as organic acid, inorganic acid, base salt, etc., and is prominently characterized by acid-base mixing, quick heating and cooling or cold / hot alternation.