Abstarct: Our purpose in this project, is writing a computer program for analysis of flow in pipe networks in steady and transient states. For this purpose we use the linear theory method for analysis of steady state flow in pipes of network, because in this method we don’t need the first guess for solving then problem. And on the other hand, the result obtains sooner in this method. Finally in Transient flow, we analysis WaterHammer in pipes of network approximately by characteristics method and calculate pressure and velocity in pipes.