The fulvic acid extracted from a weathered coal (Tulufan, Xinjian, China) was first methylated with diazomethane, and then fractionated by elution column chromatography into two fractions. Forty three compounds were structurally identified from the low-molecular-weight fraction by using capillary GC-MS. These compounds belong to the following categories: (1) benzenecarboxylic, phenolic and methylbenzenecarboxylic acids, (2) alkanes and aliphatic acids, (3) naphthalene-tetracarboxylic acids, (4) dibutylphthalate and a methyl furandicarboxylic acid. The naphthalene-structure has never been found in humic and fulvic acids before.