The present invention relates to a composite of a porous substrate and one-dimensional nanomaterial, which is manufactured by a hydrothermal method. The method for manufacturing the composite of the present invention is simple and low-cost, and the one-dimensional nanomaterial is homogeneously distributed on the porous substrate with tight binding at the interface. The present invention also relates to a surface-modified composite and a method for preparing the same. The composite of the present invention which is hydrophobically modified at the surface can adsorb organic solvents such as toluene, dichlorobenzene, petroleum ether and the like, and greases such as gasoline, lubricating oil, motor oil, crude oil and the like, with a weight adsorption ratio of >10.