Preparation method of solvent-free water-based petroleum resin emulsion

The invention provides a preparation method of a solvent-free water-based petroleum resin emulsion, wherein the method comprises the following steps: weighing petroleum resin and a modifier A by using an electronic balance scale, adding the petroleum resin into a reaction kettle, heating to dissolve, adding the modifier A for pretreatment after hot melting of solids in the reaction kettle is completed; after pretreatment is completed, the modified petroleum resin melt subjected to hot melting pretreatment is subjected to heat preservation and pressure maintaining, an emulsifying agent B is taken to be dissolved with distilled water and continuously stirred to form transparent liquid, the temperature and the pressure are increased, and the modified petroleum resin melt subjected to heat preservation and pressure maintaining and an aqueous solution of the emulsifying agent B are pumped into a high-pressure homogenizer to be emulsified; and a high pressure homogenizer is cooled to room temperature and dischargin