China and Mongolia have more mutual interests in agriculture and animal husbandry, which becomes a key sector for both in trading. Practically, both countries vary in their agriculture and animal husbandry, especially on value chains, but complementary each other. How to advance the symbiosis and collaborative upgrading of agricultural and animal husbandry value chain between China and Mongolia during the global value chain reconstruction has been become a pending point in cooperation. This paper uses references and theoretical analysis, deep conversations and site investigations to study the operations, collaborative decision factors and collaborative development of agricultural and animal husbandry value chain between China and Mongolia via value chain theory and facts. Under the current digital trading environment, cross-border electric traders have higher operating efficiency in agricultural and animal husbandry value chain between China and Mongolia, help form industrial values and add values, increase its value chains and sharing. This paper reveals the symbiosis mechanism of agricultural and animal husbandry value chain between China and Mongolia from symbiosis operation mode, collaboration mechanism and products extension, and presents upgrading mechanism form collaborative decision drives, factors and paths. This paper provides references for China and Mongolia to realize symbiosis and upgrading in agricultural and animal husbandry value chain, to deepen trading and to materialize “five missions” of Inner Mongolia.