Abstract: The present disclosure provides a continuous strengthening device comprising a bracket, at least a strengthening furnace located below the bracket and at least a pre-heating/annealing furnace movably located on the bracket. The strengthening furnace comprises a first furnace body having a first opening located on the top and a first movable furnace cover movably located on the top of the first furnace body for sealing the first opening. The pre-heating/annealing furnace comprises a second furnace body having a second opening located on the bottom and a second movable furnace cover movably located on the bottom of the second furnace body for sealing the second opening. In operation, whilst the pre-heating/annealing furnace moved onto the strengthening furnace, the first movable furnace cover and the second movable furnace cover both open, so that furnace bodies of the pre-heating/annealing furnace and the strengthening furnace are connected to form an airtight space.