The oil and gas industry has increased so rapidly and so has the complexity of the problems caused by higher technology the people use. As a result, gas production and transmission are getting more complex nowadays. On the other hand, human population growth needs more energy supply, including gas. To maintain the supply balance with the demand, gas production optimization is much needed. The optimization method is developed from existing mathematical and fluid properties modeling that have been widely used in oil and gas industry, based on real cases.The aim of this paper is to calculate pressure distribution of gas flow in complex pipeline network. Equation model used in this paper is Weymouth which is expressed in linear form by utilizing Linear Theory Method. Network analysis model was originated from Kirchhoff's Law. A continuity equation can be obtained for each node by applying Kirchhoff's first law to that node in a network. Some study case using hypothetical data has been successfully simulated and the results of calculating pressure distribution were compared with commercial software.