With ICP-OES and GC-MS, respectively, the content of mineral elements and fatty acids is determined in the larvae of Protohermes costalis (Walker) distributed in Dong River basin of Xiangxi Autonomous Prefecture. The results showed that the larvae were rich in mineral elements. The content of major elements from high to low was K, Ca, Mg and P, with the content of K up to 5 206.00 μg/g. That of trace elements from high to low was Fe, Zn, Mn, Cu, Ba, Se and Co, with the content of Fe and Zn being 520.75 μg/g and 154.15 μg/g, respectively. The harmful element Al was not detected, but the content of Cd was up to 0.878 μg/g, which was higher than the Cd content standard in Pollutant Limit in Food (GB2762 2017). The content of fatty acids in the larvae was more than 30% of the dry weight. A total of 11 peaks containing 8 fatty acids were separated. The saturated fatty acid and unsaturated fatty acid accounted for 55.4% and 44.862% of the total fat, respectively, and the essential fatty acid was 0.8%. It is concluded that the P. costalis larvae are rich in mineral elements and fatty acids. However, for the putative enrichment of Cd it is suggested that the P. costalis larvae for food should be collected from rivers and streams with high-quality water.