The utility model relates to a vacuum packaging machine with an adjustable sealing device. The utility model belongs to the technical field of vacuum packaging machines. The device comprises a feedingpart, a conveying part and a sealing part, wherein the feeding part is fixedly connected with the conveying part, the sealing part comprises a supporting assembly, an adjusting assembly and a sealingassembly, the supporting assembly is matched with the conveying part in an abutting mode, the adjusting assembly is located below the sealing assembly, the sealing assembly is fixedly connected withthe supporting assembly, and the sealing assembly comprises a driving part and a sealing part. According to the utility model, the driving motor drives the positioning frame to move vertically; the abutting air cylinder enables the first blocking plate to abut against and connect the packaging bag with the second blocking plate. The thermoplastic vacuumizing piece at the lower end of the positioning frame conducts vacuumizing and sealing operation on the packaging bag, and when food in the packaging bag needs to be dosed or when the food in the packaging bag needs to be dosed, the driving motor drives the driving gear to rotate, so that the positioning frame vertically moves to drive the thermoplastic vacuumizing piece to move, and therefore heat sealing is conducted on different positionsof the packaging bag.