The invention provides an efficient evaporator. An efficient distribution measure combining primary distribution with secondary distribution is adopted at a distribution segment to guarantee the sufficient distribution of heavy raffinate at a heating segment; an efficient collection measure is adopted at the outlet of the heating segment to effectively prevent the back mixing of the heavy raffinate; a defoaming structure is adopted at a separation segment to prevent liquid entrainment; and in addition, the design of the entire evaporator can ensure the operation of the equipment in a high vacuum degree, and the used efficient evaporator involves no transmission component and is static equipment, thereby reducing the air leakage possibility of the transmission component, and thus the high vacuum degree of the evaporator is guaranteed.