The invention belongs to the technical field of polyvinyl chloride processing, in particular relates to an improved cross-linking polyvinyl chloride resin and further discloses a preparation method of the improved cross-linking polyvinyl chloride resin. According to the preparation method of the improved cross-linking polyvinyl chloride resin provided by the invention, on the basis that a PVC (polyvinyl chloride) resin is prepared by using a conventional suspension method, a water-soluble alkyl monohydric alcohol mixed solution of an oligomer of allyl methacrylate, poly(ethylene glycol) diacrylate or poly(propylene glycol) diacrylate is finely selected as a composite cross-linking agent, and in a reaction mode that the composite cross-linking agent is put into a reaction system with a vinyl chloride polymerization conversion rate within 0.1-65%, the content of a cross-linking phase in the prepared polyvinyl chloride resin can be effectively controlled, generation of "fish eye" defects in the resin can be remarkably reduced, and the polyvinyl chloride resin with a cross-linking structure with good appearance quality can be prepared.