A Study on chemical properties of lowmolecularweight organic reducing substances was carried out by multi-disciplinary means, involving electroanalytical chemistry, biochemistry and organic chemistry. Its principal results were presented as follows:Low-molecular-weight organic reducing substances were substances, consisting of -COOH and -C^=O_-NH2 functional groups, phenol compounds, and volatile organic acids, with isoelectric points varying between 3.5～9.5, peak potentials mostly distributed in range of 0.00～0.70 V depending on components different in reducing strength, negatively charged organic reducing substances accounting for 70%～80% of the total, and apparent molecular weight being less than 500～1 000. They demonstrate obvious voltammetric behaviors in electrode process.