The invention discloses a slag quenching system, which comprises a tipping device, wherein the tipping device is provided with a tundish; the front of the tundish tipping device is provided with a granulator; an explosionproof quenching tank is arranged in the spraying direction of the granulator, and is connected with a dehydration and deslagging device through a sluiceway; a feed belt is arranged below a tapping device of the dehydration and deslagging device; one end of the feed belt is connected with a bunker; and a drainage ditch is arranged below the dehydration and deslagging device and is connected with a circulating water tank. A slag quenching process comprises the following steps of: 1, pouring slag of a slag ladle into the tundish; 2, pouring the slag in the tundish into the explosionproof quenching tank, quenching the slag by spraying water mist through the granulator, making granulated slag fall into the explosionproof quenching tank, flushing the explosionproof quenching tank to make the slag and water in the explosionproof quenching tank enter the sluiceway, and making the quenched slag enter the dehydration and deslagging device; and 3, making water separated by the dehydration and deslagging device fall into the drainage ditch and flow into the circulating water tank, and transporting the separated slag to the bunker for storage.