Experimental studies on the absorption of attapulgite and the effect of attapulgite on the mecbanic properties of composites are dealt with in this paper. The results of the experiments indicate that attapulgite has a strong absorption effect on organic matters, especially on those that possess polarityor polarity groups. The absorption of attapulgite is attributed to the electric unsaturation at the surface of the attapulgite crystal and in the channel of zeolitic water resulting from its spscial structure. Attapulgite can be used as the filling material of phenolphthalein poly (ether ether ketone) composites (PEK--C). By pretreating the attapulgite With aldehydes such as butyral-dehyde and benzaldehyde, the interfacial adhesion between the filler and thematrix can be improved, and thus Young'S modulus, tensile strength and elpngation at break of composites can be enhenced. Acetalation with benzal-dehyde gives better filler-matrix bond and enhances the tensile properties of the composites more effectively than acetalation with butyraldehyde.