The invention discloses a preparation method of soft product plastic special polyvinyl chloride resin, wherein the preparation method comprises the following steps: successively adding a dispersing agent and deionized water into a reaction kettle, stirring evenly, and adjusting the pH value of the solution to 6-7; followed by successively adding an initiator, a vinyl chloride monomer and a defoaming agent, controlling the stirring speed, stirring evenly, heating to 58+/-2 DEG C, controlling the kettle pressure, and carrying out a reaction for 4-5 hours; and adding a terminator, carrying out gas extraction and drying to obtain the high-end polyvinyl chloride resin soft product. The soft product plastic special polyvinyl chloride resin has the advantages of low apparent density, high oil absorption rate, small average particle size, and good plasticization performance, and the product has the characteristics of high processing transparency, low processing torque, and large melt index; the soft product plastic special polyvinyl chloride resin can replace ethylene-process PVC, can be widely applied in preparation of thin films, leather cloth, plastic sandals, shoe soles and various soft products, and is the soft product special polyvinyl chloride resin having good processing performance.