In this paper, author studied the relationship between the upstream enterprise and downstream enterprise of industry chain in the symbiotic theory. Author think that the enterprise between the upstream enterprise and downstream enterprise of industry chain will build a symbiotic relationship in facing the uncertainty of market under the fierce market competition, and the stability of this symbiotic relationship will be built by the object to establish a symbiotic relationship, and the choice of object depends on the degree that each enterprise obtain the market information, under the incomplete information, the enterprises will choose the object through using the rules of the degree of closeness and the rules of the degree of correlation, under the incomplete information, the enterprise will use the rules a competitive selection rules, thus, which will establish a stable symbiotic relationship among them.