The invention discloses a fermented feed device, system and method. The fermented feed device comprises an upper box body, a lower box body, a rotating wheel, a flexible sliding strip, an automatic resetting plate, a movable plate, a discharging baffle, a capacity block, a pulley, a first traction rope, a plug piece, a second traction rope, a third traction rope, a fourth traction rope, a tensionspring, and adjustment wheels. The lower part of the upper box body is detachably connected to the upper part of the lower box body to form a box body; the fermented feed system comprises the fermented feed device, a dry feed storage tank, a horizontal host, a feed delivery tube, a bacterial liquid tank, solenoid valves, a flow meter, and a first controller. The fermented feed device, system and method solve the problem of packaging and storage of a traditional high-activity fermented feed product under the premise of not drying the high-activity fermented feed product, and the feed product isconvenient for the feeding operation of farms.