The invention discloses a nitrile-butadiene rubber/attapulgite nanocomposite, a nitrile-butadiene rubber/attapulgite nanocomposite vulcanized rubber and a preparation method thereof. The preparation method of the nitrile-butadiene rubber/attapulgite nanocomposite includes the steps of: 1, dispersing an unmodified attapulgite, a dispersant, and a surface modifier in water, and preparing an attapulgite suspension; 2, mixing the attapulgite suspension prepared in the step 1 with a nitrile-butadiene rubber latex, keeping the temperature in the range of from 30 to 60 DEG C and stirring a mixing solution for 10-30min; and 3, adding a flocculating agent into the mixing solution in the step 2, performing flocculation, dewatering and drying, and preparing the nitrile-butadiene rubber/attapulgite nanocomposite. The preparation method of the invention can finish the attapulgite modification and dispersion and the mixing of the nitrile-butadiene rubber in one step. A preparation technology is simple, the operability is strong, and the industrialization application is easy.