The invention discloses a mechanical arm system assisting a person with upper limb disability in dining and a work method of the system. The system comprises a mechanical arm, an instruction input device, a rotating disc system, a plurality of special feeders, a work platform, a mouth positioning device and a controller; request signals are transmitted to the controller through the instruction input device; the controller controls a rotating disc to rotate, the feeders are rotated to the work position close to a mechanical arm, and according to voice instructions sent out by the aided person, the controller controls the mechanical arm to achieve action of special feeder grabbing. The teaching reappearing control method is reasonably combined with the man-machine interaction control method, the problem that robot teaching reappearing operation cannot adapt to changes of a work object is solved, the defect that generally, only the man-machine interaction type control method is used for operating, and operation instructions are tedious is overcome effectively, and design of the special feeders is fully used for greatly reducing the requirement of operation action complexity.