The invention discloses a device for preparing a heat-resistant contractive lithium-ion battery separator and application thereof. The device comprises an extrusion device, a cooling roller device and a drying device. The cooling roller device comprises a first casting strip roller, a second casting strip roller and a third casting strip roller, wherein the second casting strip roller is positioned between the first casting strip roller and the third casting strip roller, and the drying device comprises a plurality of transferring rollers arranged in the broken line. The device for preparing the heat-resistant contractive lithium-ion battery separator is capable of improving the preparation technology of the battery separator, improving the whole performance of the prepared battery separator, and preparing the lithium-ion battery separator with good heat-resistant contractility and good combination property.