The invention relates to a green curtain system for an external vertical surface of a floor type construction. A frame of a uniformly planned air condensing unit is arranged on the external vertical surface of the construction; a condensate water collecting tank is fixedly arranged on the lower part of the frame; a filtering device is arranged in the condensate water collecting tank; the condensate water collecting tank is communicated with an air conditioner condensate water draining pipeline; an overflow pipe is arranged at the bottom of the condensate water collecting tank; an overflow port of the overflow pipe is connected with a rope for the cirrus growing; the bottom of the rope is connected with a planting tank on the top of the lower-layer air condensing unit; a longitudinal area between the adjacent upper and lower floors as well as the collecting tank at the upper layer and the lower layer air condensing unit is formed into a green curtain unit. The green curtain system provided by the invention is used for effectively solving the irrigation problem of the green curtain plant in summer; rainwater and condensate water are utilized to irrigate; the energy is saved and the efficiency is high; the design trend of the green construction is met; the structural arrangement is reasonable; no manual maintenance is required; the stretchable overflow pipe can be used for conveniently adjusting the water level in the condensate water collecting tank, so as to balance the irrigation volume and the water storage volume.