The invention discloses a fermented feed device, system and method. The fermented feed device includes an upper box body, a lower box body, a runner, a flexible sliding bar, an automatic reset plate, a movable plate, a discharge baffle, a capacity block, and a pulley , the first traction rope, the leather plug piece, the second traction rope, the third traction rope, the fourth traction rope, the tension spring, the adjustment wheel, the lower part of the upper box body and the upper part of the lower box body are detachably connected to form a box body The fermented feed system includes the above-mentioned fermented feed device, dry feed storage tank, horizontal host, feed delivery pipe, bacteria liquid tank, electromagnetic valve, flow meter, and first controller. The invention solves the problem of packaging and storage of traditional high-activity fermented feed products without drying the high-activity fermented feed products, and facilitates the feeding operation of farms.