The invention discloses a process for preparing garbage derived fuel by coupling hydrothermal pretreatment. The preparation process comprises the following steps: performing bag breaking and sorting on municipal solid waste to obtain flammable components; then crushing the flammable components; then putting the crushed flammable components and deionized water into a high-temperature and high-pressure reaction kettle for hydrothermal treatment; adding a binder, and stirring to form a mixture; finally performing extrusion molding and hot air drying to obtain a finished product. By adopting the process, garbage materials can fully and evenly undergo a hydrothermal reaction with lower energy consumption, and water in the garbage materials is removed in a liquid form, thereby reducing the number of main hydrophilic oxygen-containing functional groups, and greatly changing the physical void structure of the derived fuel. In addition, the purposes of degrading dioxins and fixing heavy metalscan be realized through the hydrothermal treatment. Therefore, the obtained garbage derived fuel has the advantages of high heat value, stable combustion, easiness in transportation and storage, low pollutant emission and no heavy metal pollution, and the reduction, harmlessness and resource utilization of domestic garbage are realized.