In the petrochemical industry, multiphase flow, including oil–water two-phase stratified laminar flow, is more common and can be easily obtained through mathematical analysis. However, there is no mathematical, analytical model for the simulation of oil–water flow under turbulent flow. This paper introduces a two-dimensional (2D) numerical simulation method to investigate the pressure gradient, flow field, and oil–water interface height of a pipeline cross-section of horizontal tube in an oil–water stratified smooth flow, which has field information of a pipeline cross-section compared with a one-dimensional (1D) simulation and avoids the significant calculation required to conduct a three-dimensional (3D) simulation. Three Reynolds average N–S equation models (k − Ε, k − ω, SST k − ω) are used to simulate oil–water stratified smooth flow according to the finite volume method. The pressure gradient and oil–water interface height can be computed according to the given volume flow rate using the iteration method. The predicted data of oil–water interface height and velocity profile by the model fit well with some available experiment data, except that there is a large error in pressure gradient. The SST k − ω turbulence model has higher accuracy and is more suitable for simulating oil–water two-phase stratified flow in a horizontal pipe.