The invention discloses a sheet storage tensioner with an automatic tension adjusting function. The sheet storage tensioner comprises a rack, synchronous chain wheels, synchronous chains, a movable roller base, a movable roller, movable roller sliding shafts, air cylinders, air pipes, an electromagnetic valve, an air inlet pipe, an air compressor, a pressure meter, an electric pressure adjuster, via rollers, bearing blocks, bearings, pressure sensors, gaskets and a controller. According to the sheet storage tensioner with the automatic tension adjusting function, tension is adjusted through the air cylinders, high tension is achieved, the controller is adopted for achieving automatic adjustment of tension, and the problems indicated in the background art are effectively solved.