The invention provides a production system for producing potassium chloride from large grain carnallite. The system comprises a screening device, a concentrating device, a size mixing device, a reverse flotation device, a low-sodium thickener, a cold crystallization device and a coarsely potassium refining device which are connected sequentially, wherein the screening device comprises a screeningmachine and a crushing machine. The provided production system for producing the potassium chloride from the large grain carnallite is additionally provided with a set of circular crushing device at the most front end of an original process system, the large grain carnallite is fundamentally crushed into a material with the grain size meeting the process requirement, the large grain carnallite isprevented from entering the system and blocking a pipeline; and the problem that the flotation reaction is insufficient because the large grain carnallite is deposited in a flotation system and occupies the space of the flotation reaction is avoided.