The invention discloses an alfalfa dehydration silage harvesting technology and a harvester, and belongs to stockbreeding machines. Through the harvesting technology and the harvester, the field airing is not required, weather influence is avoided, the harvesting is performed at the best cradling period of alfalfa, multiple operation links of harvesting, dehydrating, cutting up, compacting and bagging and the like are finished at a time, the operation processes are reduced, the harvesting time is shortened, the investment cost on the machine is lowered, and the labor force is saved; and meanwhile, prepared silage alfalfa is small in package and is convenient to carry, and the commercialized production is easy to realize. Squeezed juice can directly flow into the field as liquid fertilizer or can be collected to feed flocks and herds, poultry and the like.