The invention relates to the technical field of aquaculture and technology for raising a precious marine product of abalones, in particular to a method and a device for raising abalones by open-type net cages. By the method and the device, a new mode for raising abalones in southern and northern provinces is realized, and a high-efficient environment-friendly mode for raising abalone-kelp integrated culture is formed. Compared with the conventional suspension cage culture, the small open-type net cage culture has smoother water flow and is more convenient to operate, particularly the phenomenon that the abalones are dehydrated due to lifting feed is avoided, so that the survival and the growth of abalones are benefitted. The raising capacity of one small net cage is close to 20 times that of one suspension cage; and simultaneously, because the small net cage culture is open, pollution to marine environment is avoided, and the device and the method accord with the ecological idea of sea ranching.