The utility model discloses a unit curtain wall assembling device, mainly comprising two glasses, two columns, rubber strips and a support column. The two columns are jointed by mutual sheathing method and fixed by the rubber strips. The support column is fixed to one of the columns, and the support column is formed to I shape. The column fixed to the support column is formed a guide groove fitting to the support column. When the unit curtain wall assembling device is stressed, the whole body is stressed because of the installation of the support column. This method can makes the stress equally, and the opening of the column can not expand to the two sides, so the water tightness and the air tightness of the rubber strips won't lose its effect. Consequently, the two columns can not be separated, and the assembling structure of the unit curtain wall can achieve the purpose of stability.