A packing mechanism for filling a space bag with a filling material is suitable for an automatic mushroom production machine. The packing mechanism includes a packing feeding mechanism and a holding mechanism. The packing feeding mechanism can feed the filling material into the space bag through the discharging hole. The holding mechanism can bear the bottom of the space bag and move up and down, so as to control the filling amount of the filling material in the space bag.一種用以將一填充料填入一太空包的填料機構，適用於一菇類自動化生產機台，該填料機構包含一填料饋送機構及一保持機構，該填料饋送機構能將填充料經由出料孔饋送至該太空包內。該保持機構能承載於太空包的底部並升降移動，從而控制太空包中的填充料的填充量。
