The pretreatment process involves separation and size reduction. Separate the recyclables, combustibles, organics, through the sorting system. There are only three final products of this pretreatment line: high-quality alternative fuels (RDF/SRF) with a particle size of 98% less than 60mm, alternative raw materials based on inorganic substances, and recyclable iron. The entire processing process does not require manual intervention, and the material compatibility is good, and there is no fear of large garbage, spring mattresses and other foreign objects. Shredder and sorting machines as a core equipment have the stable working performance, which guarantee the low cost of RDF preparation.