The invention discloses a multi-split fresh air dehumidifying unit, which comprises a compressor, a first condenser, at least two second condensers, at least two throttling elements, at least two evaporators and at least two boxes. A fresh air channel is arranged in each box, each second condenser and the corresponding evaporator are positioned in the corresponding fresh air channel, each second condenser is close to an air outlet side of the corresponding fresh air channel, and each evaporator is positioned on an air inlet side of the corresponding fresh air channel; the fresh air channels are respectively arranged in all the boxes, the various evaporators and the various second condensers are respectively positioned in the corresponding fresh air channels, the second condensers, the throttling elements and the evaporators are correspondingly connected by connecting pipes to form fresh air pipelines, and the fresh air pipelines, the compressor and the first condenser are connected to form a heat exchange working medium circulating loop after the fresh air pipelines are connected in parallel. The multi-split fresh air dehumidifying unit has the advantages that an indoor space can be effectively saved, and energy consumption is reduced.