The invention discloses a method for duplicating the operation sites of a mechanical arm. The method comprises following steps: teaching operation sites of a first mechanical arm, setting an identification pattern on the tail end; duplicating the operation sites to a second mechanical arm, utilizing a camera arranged on the second mechanical arm to automatically trace and shoot the identificationpattern, carrying out coordination conversion, setting a positioning pattern in a work space, using the camera to shoot the positioning pattern, deciding the reference points of the work sites of a workpiece, and teaching the second mechanical arm. The teaching method is simplified.