The modified attapulgite / natural rubber composites (MANRC), attapulgite / natural rubber composites (ANRC) and carbon black N330 / natural rubber composites (CBNRC) were prepared by co-coagulating rubber latex and clay aqueous suspension,respectively. The modified attapulgite was attained by dispersion with an ultrasonic cell pulverizer first and then modification with cetyltrimethylammonium bromide (CTAB). The micrographs of field emission scanning electron microscope (FESEM) and environmental scanning electron microscope (ESEM) showed that the CTAB-modified attapulgite have the best dispersibility in the composites. The mechanical properties of MANRC are the best. The best properties of MANRC can be obtained when 20phrCTAB-modified attapulgite was added, the tensile strength, the 200% tensile modulus, the tear strength and Shore A hardness increased by 58.2%, 109.3%, 46.0%, 27.8%, respectively, compared with CBNRC.