This article aims to establish a coupled thermo-hydraulic mathematical model for steam network by adopting a set of equations, i.e., the continuity equation, motion equation, energy equation, state equation and enthalpy equation and considering the interaction of hydraulic and thermal working conditions. The model is simplified according to steam flow features in pipe networks. The unsteady flow model is simplified to a steady one with considering engineering practice and the solution to the governing equations are obtained by using the standard fourth-order Runge-Kutta method. Many factors of steam flow are generally considered, such as condensability, change of state, friction and heat transfer in the model. It is concluded that coupled iteration can be employed in steam network thermo-hydraulic computation. The numerical results with the model are basically in accordance with practical operation data. This article aims to establish a coupled thermo-hydraulic mathematical model for steam network by adopting a set of equations, ie, the continuity equation, motion equation, energy equation, state equation and enthalpy equation and considering the interaction of hydraulic and thermal working conditions. The unsteady flow model is simplified to a steady one with considering engineering practice and the solution to the governing equations are obtained by using the standard fourth-order Runge-Kutta method. Many factors It is said that coupled iteration can be employed in steam network thermo-hydraulic computation. The numerical results with the model are basically in accordance with with practical operation data.