Abstract: The common method for the determination of Au in geological samples is by Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) after enrichment by polyurethane foam (PUF). Compared with activated carbon, PUF has a good selectivity but has a low absorption capacity. PUF loaded by different extraction agents or modified with different functional groups can improve the absorption capacity. PUF was treated with hydrochloric acid to prepare PUF-NH₂. Infrared Spectrum and Scanned Electron Microscope results show the peak of PUF-NH₂ shows obvious red shift, and the amount of amino group increases obviously. Macromolecule of PUF-NH₂ shows obvious fracture. The amino group after hydrolysis is reduced, which is easy to achieve in an oxide-reduction reaction with Au ions during the absorption of Au to form Au nanoparticles. Modified PUF-NH₂ achieved absorption capacity of 96 mg/g, which is an 8-fold improvement compared to PUF. Using PUF-NH₂ to enrich Au in geological samples, the samples were first ashed and then digested by 50% aqua regia. Gold was determined by ICP-OES. The recovery by standard-addition ranged from 95.0% to 105.0% and the detection limit was 0.15 μg/g. The experimental results show that the enrichment degree and analytical sensitivity are improved by using PUF-NH₂, which is suitable for the determination Au in low grade ores.