The invention discloses a silk stocking automatic folding mechanical structure and a folding method thereof. The mechanical structure comprises conveyor belts, belt pulleys, a motor, a crank mechanism, an inner paperboard conveying rail, a vacuum adsorption disc, a guide pulley and a photoelectric sensor. The motor drives the crank mechanism so as to drive crank to rotate. An inner paperboard adding mechanism comprises the inner paperboard conveying rail, the vacuum adsorption disc and the guide pulley. The silk stocking automatic folding mechanical structure is simple and reasonable, the folding method is simple, the whole operation performance is good, and high efficiency is achieved. A silk stocking folding machine can work through complicated equipment such as manipulators, but the cost of the silk stocking folding machine is high, so that common enterprises do not have integration capability. The silk stocking automatic folding mechanical structure is low in cost, so that the enterprises can perform integrated arrangement. According to the design of the mechanical structure and by employing the mechanical structure, the labor intensity of workers can be hopefully reduced, and the folding efficiency and quality of silk stockings can be improved.