The invention relates to a processing method and a processing system for kitchen garbage resourcilization. The processing method comprises waterpower decomposition, fragmentation, sorting, dehydration, crushing, anaerobic fermentation and oil-water separation; the processing system comprises a feeding device, a waterpower conveying decomposition tank, a fragmentation preselection apparatus, a dehydration crushing apparatus, an anaerobic fermentation mixing apparatus and an oil-water separation apparatus. The method and system provided in the invention adopt sorting by using water. Advanced treatments of sorting to remove impurity, fragmentation, dehydration, desalination, oil removing and the like are automatically carried out to substances of different properties in the kitchen garbage by using water as a carrier combining with mechanization equipment, according to dissolvability and different proportion of the substances; organic substances separated from the kitchen garbage are fermented and prepared into organic fertilizers; and grease in separated oil-contained sewage is recycled by oil-water separating. The method and the system in the invention thoroughly remove substances of oil, salinity, soy sauce, vinegar and the like in the kit garbage that against fermentation composting. The method and the system have the characteristics of high removal rate of salinity and grease, high dehydration efficiency, good automatic sorting effect, realization of resource regeneration and no secondary pollution.