The invention discloses an automatic lifting device with a liftable support. The automatic lifting device comprises an air cylinder bracket, a tool plate, the liftable support, an air cylinder, a fixing plate and a clamping-connecting plate fixed to the fixing plate, wherein the liftable support, the air cylinder, and the fixing plate are fixed to the tool plate. The liftable support is a rectangular frame provided with a lifting drive part. The top end of the air cylinder bracket is provided with two air cylinder fixing plates, and the cylinder body of the air cylinder is fixed to the air cylinder fixing plates. The fixing plates are fixed to a piston of the air cylinder. The clamping-connecting plate comprises two side plates provided with T-shaped grooves. Driving heads comprise the ascending driving head and the descending driving head. The ascending driving head includes an ascending driving board provided with a U-shaped groove. The descending driving head includes a descending driving board provided with an R-shaped groove. The automatic lifting device with the liftable support has the advantages of being capable of holing up and putting down the liftable support conveniently and quickly, improving the working efficiency of a tool plate production line, being simple in structure, lowering the production cost and the like.