The invention relates to a device system for efficient cobalt sulfate concentration and continuous crystallization. The device system provided by the invention comprises an evaporation heater (06), an evaporation separator (07), an OSLO vacuum crystallizer (17), a fine grain eliminating heater (16), a steam compressor (10), a condensate water preheater (03), a steam preheater (04), a centrifugal machine (20) and a pump. A stock solution enters the evaporation heater through the preheater, and the heater is connected with the separator and the circulating pump; the separator is connected with the OSLO vacuum crystallizer; a material liquid drop device is arranged in the middle of the OSLO vacuum crystallizer, a flash chamber is arranged at the top of a pipe, a circulating liquid outlet is formed in the side part, a secondary steam outlet is formed in the top of the flash chamber and is connected with a condenser and a fine grain eliminator, the crystallizer is connected with the centrifugal machine, and the centrifugal machine is connected with a mother liquid tank and a stock solution buffer tank to realize overall material liquid circulation. The system has the characteristics of energy conservation, continuity, automation and high efficiency, and obtained products are large in grain size and high in quality.