Vitamins mean life-sustaining factors and are important nutrients necessary for normal life activities of pigs. Various vitamins have different structures, nutritional functions and physiological functions. Vitamins can participate in the corresponding metabolic activities as components of many enzymes. Vitamins can't constitute body tissue components and can't supply energy. Although the demand is small, it has great functions, mainly regulating the metabolism of the body. Lack of any one will make the physiological function of the body out of balance, leading to vitamin deficiency. Most vitamins cannot be synthesized in pigs. Even if some vitamins can be synthesized in the body, they are often too slow or too little to meet physiological needs. Therefore, vitamins must be supplemented regularly through feed. Green and juicy feed is rich in vitamins, and the supply of vitamins is easy to reach a balance after harvesting, preservation, preparation and reasonable feeding. Therefore, feeding pigs with green and juicy feed is one of the effective ways to supplement vitamins. In pig farms with concentrated feed or pig farms that can't feed green feed, a proper amount of multivitamins must be added to pig feed to meet the needs of pigs for vitamins and prevent vitamin deficiency.