The utility model provides an automatic expanded vacuum and outer diameter adjusting device for a heat shrink tube as well as heat shrink tube expanding equipment. The automatic expanded vacuum and outer diameter adjusting device for the heat shrink tube comprises diameter measuring instruments, a controller, a servo motor, a linear motion guide rail and an aperture adjuster. The provided automatic expanded vacuum and outer diameter adjusting device can obtain data according to real-time outer diameter of a product, is compared with a preset standard outer diameter value, controls the servo motor to rotate, then drives the aperture adjuster to act and automatically controls the vacuum in a vacuum box of the expanding equipment, meanwhile, internal and external pressure difference of the product is adjusted, the outer diameter of the product is adjusted, real-time continuous adjustment of the outer diameter of the product can be realized, intelligent adjustment for an expanding process can be improved, and the production stability and product quality can be improved.