The invention provides a roof and gable joint, and relates to the technical field of buildings. The roof and gable joint is used for connecting a roof and a gable, the roof and gable joint cannot damage the structural integrity of the roof, and can ensure a waterproof effect of the roof, the roof comprises a roof plate, the gable comprises a flashing plate, the roof and gable joint mainly comprises a mounting assembly and a fixing assembly which are connected with each other, and the roof plate is mounted on a rooftop through the fixing assembly, so that the free end of the roof plate is fixed, and it is ensured that the roof has the good waterproof effect. According to the roof and gable joint, the fixing assembly can provide a fixing position and an installation supporting platform for the roof and gable joint, the flashing plate is installed on the mounting assembly, the mounting assembly is fixed to the rooftop and abuts against the fixing assembly, the mounting assembly can provide an installation fixing platform for the flashing plate, damage to the roof plate possibly caused by direct connection of the flashing plate and the roof plate is avoided, through the connection of the mounting assembly and the fixing assembly, the roof plate and the flashing plate are connected and fixed, and then the roof and the gable are connected with each other.