The invention provides an armor layer deformation monitoring system, apparatus and method for a submarine cable. The armor layer deformation monitoring system includes an external diameter measuring module, a control module, and an alarm module, wherein the external diameter measuring module is used for obtaining the external diameter of a submarine cable to be measured; the control module is electrically connected with the external diameter measuring module for receiving the external diameter of the submarine cable, obtained by the external diameter measuring module, and determining that thesubmarine cable to be measured lifts and emitting a driving signal; and the alarm module is electrically connected with the control module for receiving the driving signal and emitting a cage liftingsignal. The armor layer deformation monitoring system can obtain the external diameter of the submarine cable to be measured through the external diameter measuring module so as to determine whether the submarine cable to be measured lifts so as to emit a cage lifting signal through the alarm module when the submarine cable to be measured lifts, thus being convenient for prompting the operator towait for the submarine cable to be measured to lift so as to adjust a dragger for conveying the submarine cable to be measured to avoid cage lifting of the submarine cable to be measured so as to avoid damaging the submarine cable.