The invention relates to agricultural equipment, and in particular relates to a multifunctional large-scale rain-dropping machine. The large-scale rain-dropping machine is mainly used for timely irrigating, supplementing water, supplementing fertilizer, weeding as well as preventing and curing plant diseases and insect pests for the crops on a large area at the dry farming area plain and the sloping field farm, so that the growing environment quality of the crops can be effectively improved independent of rainwater, the most timely and proper management maintenance, such as watering, topdressing, weeding, spraying in an atomizing way, spraying smoke and powder, and preventing plant diseases and insect pests can be obtained during the automatic monitoring in the whole growth process of the crops, and the production increase and the income increase of the crops can be guaranteed. The large-scale rain-dropping machine mainly comprises 1, a lifting work platform; 2, a left-lifting multi-stage hydraulic cylinder; 3, a left-injection pipe; 4, a fan-shaped rotary box; 5, a swing hydraulic cylinder; 6, a fixed connecting trunnion base between a rotating support and the swing hydraulic cylinder; 7, a middle injection pipe; 8, a rotary injection pipe fixing base frame; 9, a right-lifting multi-stage hydraulic cylinder; 10, a fixed connecting shaft for the head of a piston rod of the swing hydraulic cylinder; 11, a right injection pipe and the like.