The triple effect falling film evaporator is a system in which three falling film evaporators are connected in series and operated in series. The first effect uses fresh steam, and then the secondary steam generated by the first effect due to heat evaporation enters the second effect as a heat source for the second effect evaporator. The secondary steam generated by the second effect heated evaporator enters the third effect as a heat source for the third effect evaporator. Equivalent to steam being utilized three times. To achieve the goal of energy conservation and consumption reduction. Reduced steam consumption and also reduced the condensation of secondary steam evaporated. Therefore, the steam consumption ratio of the triple effect falling film evaporator is generally around 0.4~0.45.