Landfill leachate treatment by Reverse Osmosis (RO) system was evaluated in this study. Operational conditions of sand filters, sulfuric acid dosing and pH adjustment, cartridge filters and cat pumps, and membrane modules were discussed in detail. Advantages and challenges of RO for leachate treatment in developing countries handled with sustainability logic. The system has been successfully applied in leachate treatment with high removal rates as 98% of COD, 99% of total Nitrogen and suspended solids and substantial heavy metal removal. However, high costly operating expenses, dependency on the manufacturers for membranes, chemicals and other materials indicated the system unsustainable. Especially high-strength characteristic of leachate, high energy consumption of RO process, difficulty to struggle with scaling problems, limited lifetime of membranes and management/treatment of concentrate were expressed as the constraints of the system.