The invention belongs to the technical field of limiting devices, in particular to a limit doorframe. The limit doorframe comprises a top frame and a left upright column and a right upright column. A travel switch is respectively arranged on the top frame and the left upright column and the right upright column to serve as a limit switch. A rotating plate is arranged on the lower part of the top frame, and is connected with the top frame through a hinge. The rotation of the rotating plate can move a probe of the travel switch on the top frame, so that the travel switch on the top frame is triggered to output a signal to a control system. A rotating rod is arranged on the inner side of each upright column and connected with a pin shaft. A probe of a travel switch of each upright column is inserted into a bayonet of the pin shaft. The rotating rod rotates to drive the pin shaft to transversely rotate to move the probe of the travel switch of each upright column, so that the travel switch of each upright column is triggered to output a signal to the control system. The limit doorframe can accurately automatically monitor the appearance of a transmitted object.