The invention provides a gypsum line die joint-cutting mechanism. A position monitoring device monitors the conveying position of a gypsum line die; when a joint enters a joint-cutting position, a first driving system acts, a joint-cutting bracket and the gypsum line die slip synchronously, a joint-cutting device acts to carry out joint-cutting on a joint position so as to cut gypsum lines on twoadjacent gypsum line dies apart at the joint position, and the joint-cutting bracket slips to a preset joint-cutting position to finish joint cutting; and the first driving system pulls the joint-cutting bracket to reset to an initial working position, the position monitoring device continuously works to realize continuous joint-cutting on a joint between gypsum line dies. During the gypsum line preparation process, the joint-cutting mechanism is arranged to carry out automatic joint-cutting operation on the joint between gypsum line dies, so that the working strength of manual operation is lowered, the equipment automation is improved, and the joint-cutting efficiency is improved. The invention further provides a gypsum line production line.