A model for gas-liquid annular and stratified flow through a horizontal pipe is investigated, using the two-phase hydrokinetics theory. Taking into consideration the flow factors including the void fraction, the friction between the two phases and the entrainment in the gas core, the one-dimensional momentum equation for gas has been solved. The differential pressure of the wet gas between the two tapings in the straight pipe has been modeled in the pressure range of 0.1-0.8 MPa. In addition a more objective iteration approach to determine the local void fraction is proposed. Compared with the experimental data, more than 83% deviation of the test data distributed evenly within the band of +/- 10%. Since the model is less dependent on the specific empirical apparatus and data, it forms the foundation for further establishing a flow measurement model of wet gas which will produce fewer biases in results when it is extrapolated. (C) 2016 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.