Abstract: Using evolutionary arithmetic this paper studied the modeling of thermofluid network which existed in thermopower system rifely. First, a general mathematic modeling of fluid network was established based on the basic physical laws, and then evolutionary arithmetic was adopted to identify the parameters of network. This method avoids the calculational errors of conventional methods that using experiential values or testing data, enhances the computational precision of model and makes the behaviors of model accordant to the real object. This method was used to simulate the steam network in a certain type marine power plant, and the outputs of model against the real values were measured. The results show that the parameters identified model has preferable accuracy, and the EAbased modeling method is useful.