Device and method for preparing polyolefin elastomer

The invention provides a device and method for preparing a polyolefin elastomer, the device comprises a raw material supply unit, a reaction unit and a purification unit, the raw material supply unit comprises an alpha-olefin storage tank, an ethylene storage tank, a hydrogen storage tank and a raw material mixing tank; the reaction unit comprises a screw reactor; and the purification unit comprises a flash tank and a purification tank. Alpha-olefin is used as a reaction raw material and a solvent at the same time, so that the use of the solvent is reduced; the screw reactor is used as a polymerization reaction place, has stronger shearing force, can realize good mixing of a high-viscosity system and continuous production at the same time, and effectively improves the polymerization efficiency and reduces the energy consumption compared with a traditional tank reactor; besides, the flash tank can separate unreacted monomers for recycling, energy is saved, polyolefin melt obtained through reaction is subjected