High investment highlights the importance of optimizing gathering pipeline networks. In view of the problem of ignoring hydraulic characteristics in previous studies, an integrated mixed-integer linear programming (MILP) model for gathering pipeline networks is developed in this study. Taking the minimum total construction cost as the objective function, the proposed model considers the economic and technical constraints such as obstacles, three-dimensional terrain, pipeline topological structures, pipe diameters, wellhead back pressure, and pressure equipment. The ant colony optimization algorithm is used for route optimization to provide parameters for the proposed model. Moreover, a piecewise method is employed to linearize the nonlinear hydraulic equations. Then, the model is solved by the CPLEX solver to obtain the optimal solution integrally, including the optimal connection topology, the location of the central processing facility, the position of pressure equipment, the diameter and detailed route of each pipeline, the pipeline flowrate and the node pressure. Finally, two real-world gas fields and a virtual oil field are taken as examples to demonstrate the feasibility and practicality of the model. The optimal results illustrate that this model can be implemented as a decision-support tool to optimize gathering pipeline networks in the actual design process. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.