The invention discloses a tungsten smelting slag-based water treatment ceramsite, and a preparation method thereof, and belongs to the field of smelting slag resource utilization and harmlessness treatment. The tungsten smelting slag-based water treatment ceramsite is composed of tungsten smelting slag, river sand, and an additive. The preparation method comprises following steps: tungsten smelting slag, river sand, and the additive are dried and grinded into dry powder respectively; the obtained tungsten smelting slag powder, the river sand powder, and the additive powder are weighed at a certain ratio, are mixed and stirred to be uniform, and are delivered into a granulating machine for granulating moulding; and a ceramsite finished product is obtained via drying and sintering. The surface of the tungsten smelting slag-based water treatment ceramsite is rough; the interior of the tungsten smelting slag-based water treatment ceramsite is porous; the tungsten smelting slag-based water treatment ceramsite can be taken as a water treatment filter material; resource utilization of tungsten smelting slag is realized via the preparation method; and the preparation method possesses excellent economic benefit and social benefit.