A vacuum mixer can mix raw materials and auxiliary materials in a vacuum state, reducing bubbles in the materials and increasing product elasticity. Designed as a double helix structure, the mixing shaft is equipped with inclined blade blades and spiral propulsion mixing rings, which can make the material move in both forward and reverse circular motions during the flipping process, quickly and evenly mixing the material, fully expanding without bubbles, good elasticity, bright color, and laying a good foundation for the next processing step.