This article studies the network organization of service industries under the condition of uncertainty. The post2sale service industry has already transforming into network organizations in some eastern Chinese big cities. The business is with uncertainty , so in this article we build Poisson type model to analysis the network organization ac2 cording to the characteristics of the market . We conclude from the model that the efficiency improvement of network organization mainly embodies in two aspects : 1) the scale economy of assets and management , and 2) complemen2 tary effect of personnel under conditions of uncertainty