The invention relates to a connecting and installing method of a unit curtain wall, which comprises the procedures that: a floor unit Q is hinged with a body structure in four points, which forms a banding pattern curtain wall supporting system, as same as a secondary supporting system attached to the body structure; an interlayer regular triangle unit plate A is arranged temporarily between the floor units Q, and forms a third supporting system with the floor unit Q; an interlayer inverted triangle unit plate V is arranged in the triangle opening formed by the floor unit Q and the regular triangle unit plate A, which forms a whole curtain wall system. The connecting and installing method of a unit curtain wall has the advantages of taking every floor as an independent work section, finishing installing curtain wall via the space in room, improving control ability of the time limit for a project, and adapting to more complex space curved surface.