Preparation method of IF steel for galvanized automobile outer plate

The invention particularly relates to a preparation method of IF steel for a galvanized automobile outer plate, and belongs to the technical field of steel preparation. A preparation method of IF steel for galvanized automobile outer plates comprises the steps of converter smelting, tapping, RH refining and pouring, when blowing is stopped during converter smelting, the free oxygen content of molten steel is controlled to be a first preset amount, and the carbon content in the molten steel is controlled to be a second preset amount; lime and fluorite are added before tapping; during tapping, controlling the thickness of top slag of the steel ladle to be a third preset quantity; carrying out primary modification after tapping; in RH refining, after vacuum decarburization, the residual oxygen content of the molten steel is controlled to be a fourth preset amount; after RH refining vacuum breaking, secondary modification is carried out; during pouring, a tundish with a flow stabilizer, a high retaining wall and