The invention discloses an automatic vacuum sub-packaging device for granular food products, which mainly comprises a precision measuring module system, a lining packaging bag manufacturing module system, a lining bag packaging module system, a three-jaw bag unfolding module system, a telescopic hand guiding/conveying module system, a rotating multi-port vacuum module system and an electrical control module system. By using the sub-packaging device of the structure, the double packaging and vacuumizing of linings and external packaging bags of products are effectively realized, thereby prolonging the refreshing time of the food products; a high-precision meter is used to ensure that the weights of all small bags of the food products are uniform, and the packaging appearances and shapes are consistent; and full-automatic touch screen operation is applied to the sub-packaging device to keep the food products clean and sanitary and improve the production efficiency.