Significant increases in solid waste generation and inappropriate waste management system leads to overloaded landfills, which have negative impacts on the environment and human health. Reducing waste sent to landfill has become an emerging mission in Vietnam. This study aims at assessing cost-effective solutions to reduce waste-to-landfill amount using system analysis approach. A single-objective optimisation model is formulated to minimise the cost of the system in association with different landfill waste reduction targets and values of waste separation efficiency for Hoi An city. As a result, the landfill target is directly proportional to the cost. It means the higher landfill reduction target leads to the higher cost of the system. Meanwhile, the separation efficiency is inversely proportional to the system cost. The result showed that twenty-five percent of municipal waste treated in landfills is achievable target based on the current condition of the city. Also, ten percent of municipal waste sent to landfill is an infeasible mission if the waste separation rate is too low. If waste is wholly separated at source, incineration, composting and landfill can be applied as main treatment alternatives to reduce seventy-five percent of municipal waste sent to landfill with the cost of about 1,800 USD/d.