The invention discloses a replaceable unit curtain wall panel system, comprising a unit curtain wall matrix, an aluminum alloy subframe and a glass curtain wall arranged on the aluminum alloy subframe; wherein, the aluminum alloy subframe comprises upper and lower lateral material belts and left and right vertical material belts; hanging mechanisms are respectively arranged between the upper and lower lateral material belts and the unit curtain wall matrix; telescopic positioning mechanisms are respectively arranged on the left and right vertical material belts. In the unit curtain wall system, first the aluminum alloy subframe equipped with the glass curtain wall is hung on a cross beam of the unit curtain wall matrix by the hanging mechanism and then is fixed on a vertical column of the unit curtain wall matrix by the telescopic positioning mechanism so that the four edges are fixed; when dismounting is required, the aluminum alloy subframe can be taken off only by loosening the telescopic positioning mechanism, thus, the unit glass curtain wall is replaceable and has good position limit effect and relatively long service life.