The invention discloses a flexible-to-convert multi-hearth spray tower system which comprises a spray tower and a plurality of hot air furnaces; a gate valve device is arranged in an intersection position between the spray tower and each hot air pipe; each gate valve device comprises a gate valve body and an executing mechanism; each gate valve body comprises a gate valve plate and a heat-resisting layer; each heat-resisting layer is bonded on one side of the corresponding gate valve plate; the gate valve bodies are inserted into the corresponding hot air pipes in the radial directions of the hot air pipes, so as to isolate the spray tower from the hot air furnaces; each heat-resisting layer is located on side, communicating with the corresponding hot air furnace, of the gate valve body; and the executing mechanisms can drive the corresponding gate valve bodies to make straight reciprocating motion in the radial directions of the corresponding hot air pipes, so as to control the spray tower to intermittently communicate with or be separated from the hot air furnaces. A situation that a traditional out-dated mode using laid bricks to isolate the spray tower from the hot air furnaces is low in efficiency, the time and manpower are wasted, the cost is high and the safety of operating workers can not be ensured is changed completely, and a leap-forward innovation of spray tower equipment is promoted.