The invention relates to a synthesis method for polyvinyl chloride with a high polymerization degree on the basis of Pickering emulsion type chain extender. The synthesis method comprises the following steps: firstly, preparing the Pickering emulsion type chain extender from montmorillonite solid particles with an emulsification stability function, the chain extender and the like; then, with a suspension method, synthesizing the polyvinyl chloride with the high polymerization degree. The prepared Pickering emulsion type chain extender is environmentally friendly and high in stability; the Pickering emulsion type chain extender is added in one time when being used and has the advantages of even chain extension function, high utilization ratio, good adaptation in a polyvinyl chloride suspension system, small use amount, moderate polymerization condition and relatively simple technology. The obtained polyvinyl chloride with the high polymerization degree has good resin performance, small'fisheye' amount, good product appearance, higher intensity and better environmental adaptation.