The invention discloses a device and method for recovering ethane and producing liquefied natural gas. The device comprises a liquidation cold box, a hydrocarbon liquid separator and a demethanation tower and the above parts are orderly connected. A lower outlet of the demethanation tower, a demethanation tower reboiler and a lower inlet of the demethanation tower are orderly connected through pipes. A bottom outlet of the demethanation tower is connected to an ethane recovery pipe. A top natural gas outlet of the demethanation tower, the liquidation cold tank, a first throttle valve and a liquefied natural gas pipe of the next process are connected orderly. The liquidation cold tank, a refrigerant compressor and a refrigerant cooler are connected orderly through pipes to form a refrigerant refrigeration cycling system. Through external refrigerant refrigeration cycling, ethane is recovered and liquefied natural gas is produced so that ethane and ethane-plus components are recovered and the liquefied natural gas is prepared from methane-rich gas obtained by ethane recovery. The device and method can effectively reduce investment, have good economic benefits and realize a high product yield.