The invention discloses an ionic liquid-supported polymer, the preparation method and application of the polymer. The ionic liquid-supported polymer of the invention is the copolymer of vinyl imidazole salt and polymer cross-linker. According to the invention, firstly, N- vinyl imidazole is reacted with chlorobutane to produce imidazole salt; then the ionic liquid is fixed on a solid polymer through the free radical copolymerization between the imidazole salt of ethylene and divinylbenzene. The ionic liquid-supported polymer of the invention has good catalytic activity to the reaction that epoxides and carbondioxide are reacted to synthesize cyclic carbonate through cycloaddition, therefore, the ionic liquid-supported polymer is a solid catalyst with high activity and high selectivity. Compared with other catalysts, the ionic liquid-supported polymer has simple preparation process and the firm supporting; when the reaction is finished, the reaction solution can be easily treated, and the catalyst can be filtered and separated easily and can be reused.