Multi-effect evaporation is one of the more widely used evaporation methods in the chemical production process. Due to the multi-effect evaporation equipment investment, energy losses, operating costs, etc. accounted for a large proportion of production costs; the multi-effect evaporation process has a wide range of parameters, which need to be approximated in order to better optimise the design. Therefore, a mathematical model of the multi-effect evaporation process is developed and solved using the principles of energy conservation and material conservation in this paper. The results show that the mathematical model established by the method meets the design requirements and provides a certain reference value for model research and solution of similar process systems.