The invention discloses a multi-rotary disc type molten slag centrifugal granulating system. The multi-rotary disc type molten slag centrifugal granulating system comprises a slag particle trapping unit (101), a multi-shaft rotary disc unit (102) and a power and power transmission unit (103), wherein the multi-shaft rotary disc unit (102) consists of a center rotary disc, a plurality of non-coaxial auxiliary rotary discs and the like. The multi-rotary disc type molten slag centrifugal granulating system is characterized in that the molten slag is granulated by the multi-shaft rotary discs, sothat compared with the single-shaft system, the treatment amount is larger, the space is saved, and more advantages are realized. The invention also provides a novel rotary disc structure for the granulating of the molten slag; flow guide convex blocks are arranged at the surface of each rotary disc in a center rotary symmetric way, so that compared with the common rotary disc, the size of the granulated molten slag is more uniform, and the distribution of the particle size is more centralized. The multi-rotary disc type molten slag centrifugal granulating system has the advantages that the implementing is smooth, the treatment amount of the molten slag is obviously increased, and the large-scale application of the dry type centrifugal granulating system in metallurgical industry is realized.