To address the lack of emphasis on carbon emissions in traditional airline network and fleet planning, an integrated optimization approach that incorporates carbon emissions into the planning process was proposed. The model was based on a multi-allocation hub-and-spoke network structure, taking into account route selection, demand distribution, capacity constraints and fleet size. Emissions were calculated using Environmental Protection Agency (EPA) standards, cruise phases, and a carbon tax mechanism was applied to convert emissions into cost elements, resulting in a joint optimization mathematical model aimed at minimizing airline operating costs. The model was solved using the Gurobi commercial solver. Results indicate that airlines should prioritize low-emission short-haul flights to meet market demand, and policymakers should consider gradually raising carbon tax levels to foster sustainable development in the aviation industry.