The Kardashian family is preparing for war -- gearing up to unleash a legal attack on everyone who claimed their clothing line is manufactured in child slave labor sweat shops in China ... TMZ has learned.

Sources close to the family tell us ... Kris Jenner is furious -- claiming the guy who runs the Institute for Global Labour and Human Rights had no right to accuse the Kardashian brands of wrongdoing because he has no tangible proof to back up his claims.