The invention discloses a process device and method for recycling ethane mixed hydrocarbon from LNG. The device comprises an LNG booster pump, a return fluid heat exchanger, a lean gas condenser and ademethanizing tower which are connected in sequence. A tower top gas outlet of the demethanizing tower is sequentially connected with the return fluid heat exchanger and a return fluid division tank.A gas phase outlet of the return fluid division tank is sequentially connected with a lean gas compressor and the lean gas condenser. A fluid phase outlet of the return fluid division tank is sequentially connected with a methane reflux pump and a tower top inlet of the demethanizing tower. The process device and method have the advantages that energy consumption is low, product diversification is achieved, multilevel deep utilization of the LNG is achieved, operation is flexible, and the process is simple; natural gas resources can be fully utilized; and the defect that existing crude oil resources are insufficient is made up.