The invention relates to a system and method for separating ferrous sulfate by conducting air exhaust and compression on a titaniferous solution. The system is composed of a titaniferous solution tank, a gas-liquid separator, a compressor, a contact-type condenser, a vacuum pump, a cooling tower, a cooling tower pump, a spraying pump, a liquid seal pool and a side stirrer. The large-flow compressor is adopted for the system as air exhaust equipment for vacuum flashing and cooling of the titaniferous solution, in the cooling process, a wall-dividing-type cooling wall face does not exist in thetitaniferous solution tank, partial supercooling phenomena do not exist inside the titaniferous solution, and the problem that ferrous sulfate forms crystal scars and crystal scale on the wall-dividing-type cooling wall face is solved; electric power serves as a driving energy source for the system, and cooling load is only heat released by condensation of secondary steam and heat of converted from wasted work of the compressor. Compared with a traditional system for separating ferrous sulfate by cooling a titaniferous solution, the system and method have the advantages that the running energyconsumption is low, cooling is quick, the cooling load is small, the production efficiency is high, the labor intensity is small, the crystal size is uniform, and secondary sewage is not generated.