JYC polymer microsphere emulsion was synthesized by inverse emulsion polymerization. In order to explore the expansion mechanism of polymer microsphere, the variation of JYC sizes were detected. Through physical simulation experiments, the regulation of fraction flow and the result of displacement in heterogeneous physical simulation were measured. The results showed that the size of JYC microspheres swelled and increased in water at the reservoir temperature. After 60 days maintenance , the microspheres emulsion had the best dispersion and the property of expansion was prone to stability. Moreover, The appropriate injection concentration of JYC microspheres was 3000mg/L. JYC microsphere emulsion could improve the displacement efficiency of high permeability layer effectively, and expand the swept volume of low permeability layer, and enhance the ultimate recovery in different permeability ratio reservoir models.