Plastic film tightening device

The utility model provides a plastic film tightening device. The plastic film tightening device comprises a rack, a supporting rod and a clamping assembly. The rack is of a horizontally-arranged rectangular frame structure, and telescopic devices are arranged at the two ends of the rack. The two supporting rods are vertically arranged between the two side edges of the machine frame, and the supporting rods are movably arranged along the connecting line between the two ends of the machine frame. The two clamping assemblies are arranged between the supporting rod and the end of the rack correspondingly, each clamping assembly comprises a sliding rod arranged between the two side edges of the rack, the sliding rods are connected with the end of a telescopic rod of the telescopic device, a pair of clamping plates is hinged to the upper portion and the lower portion of each sliding rod, and protruding plates are arranged on the sides, facing the supporting rod, of the front ends of the clamping plates correspondin