Abstract: The marine sediment samples were decomposed by microwave digestion and 50 elements in it were determined by ICP-MS. The two-point standard curves were plotted by blank solution and marine sediment reference materials. The microwave digestion conditions were optimized, and the analytical isotopes, internal standard elements and instrument determination modes were determined. The results showed that the detection limit of most of the elements was below 0.1 μg/g, and the RSD of each elements were between 1.2% and 12.4%. The measured value was consistent with the certified value through the analysis of national standard references of marine sediments, and the recovery of each elements in the actual sample was between 81.0% and 118.1%. 50 kinds of elements in marine sediments could be measured at the same time with very low detection limit in this method, and it was very suitable for rapid analysis of small batch of marine sediment samples because of convenience, high efficiency, and good decomposition effect.