The invention discloses a three-effect vacuum evaporation system for improving evaporation efficiency of copper sulfate. The system comprises a preheating coiler, a liquid incoming pump, a one-effectvapor-liquid separation chamber, a two-effect vapor-liquid separation chamber, a three-effect vapor-liquid separation chamber, a one-effect plate heat exchanger, a two-effect plate heat exchanger, a three-effect plate heat exchanger, a plate condenser, a water ring vacuum pump, a vacuum separation tank, a balance valve, an axial flow pump, a one-effect feeding pump, a two-effect feeding pump, a two-effect discharging pump and a control valve. By adopting the vapor-liquid separation chambers in unique design, the plate heat exchangers reasonable in model selection and a three-effect mixed flowevaporation process, both operating and cleaning are simple and easy to implement, evaporation efficiency is high, and unit consumption of vapor for using copper sulfate raw materials to produce eachton of copper sulfate is lowered by about 45%. Secondary vapor waste heat of each effect can be recycled, so that energy conservation and consumption reduction are realized; secondary vapor condensateis recycled for copper electrolysis production; continuous and automatic three-effect vacuum evaporation is realized by controlling one-effect temperature, two-effect liquid outgoing time and liquidoutgoing proportion.