The invention discloses a negative-pressure microwave uniform spraying and drying device and application, belonging to the technical field of uniform drying devices. The negative-pressure microwave uniform spraying and drying device comprises a circulating material storage device, a feeder, a negative-pressure spraying pipe, a microwave heating cavity, a cyclone separator, a vacuum storage tank, a discharger, a water ring vacuum pump, a circulating pipe and microwave sources. The circulating material storage device is used for storing materials dried circularly, the feeder is used for feeding dry materials to the negative-pressure spraying pipe which is a channel for drying and circulating the materials, and the microwave sources are uniformly distributed inside the microwave heating cavity, two ends of which are sealed. The cyclone separator is connected with an outlet of the negative-pressure spraying pipe inside the microwave heating cavity and is connected with the vacuum storage tank and the discharger through a channel. The discharger is connected with the circulating material storage device through the circulating pipe. Because the materials can be sprayed under negative pressure, the device can be used for spraying, rotating and circulating the materials under a microwave vacuum drying condition so as to achieve the purpose of drying the materials efficiently and uniformly, meanwhile, is favorable for shortening the drying time by above 40% and reducing the cost of large-scale production.