Spherical particle catalysts (PILs-XSS) were synthesized by suspension polymerization, which was characterized by SEM-EDS, FT-IR, TG, and BET-BJH. The characterization results showed that PILs-XSS had a specific core structure, a certain pore size (14.3nm), and surface area size (71.5m2/g), and remained stable at 293.4 °C. The catalyst performance was evaluated by a one-pot synthesis of dimethyl carbonate. The process conditions were optimized in detail. The optimal reaction conditions were as follows: the dosage of PILs-XSS was 2.5 wt %, the CO2 pressure was 1.5 MPa, the reaction temperature was 100 °C, the reaction time was 4 h, the molar ratio of methanol to propylene oxide （PO）was 3: 1, and the dosage of cocatalyst Na2CO3 was 3 wt %. Under the optimum conditions, the conversion of PO was up to 98.8 % and the yield of DMC reached 53.7 %.