The random size carton case corner edge side sealer is a machine that automatically adjusts the sealing structure according to the size of the carton to achieve tape protection at the four corners size of the carton; it is suitable for mixed size carton automatic packaging line applications; it is also suitable for single variety size applications; no manual intervention is required to change varieties; packaging efficiency can reach 360 cartons per hour; with the random robot case erector and random size case sealer, a complete unmanned packaging line can be achieved.