Mercury (Hg) has strong mobility, persistence and high bioconcentration, Hg and its compounds are important heavy metal pollutants in the ocean. Through the difference and stability experiments between the groups of standard curves, the technical details of DMA to determinate the total mercury in marine sediments are discussed by using mathematical statistics. Compared with the traditional national standard method—atomic fluorescence spectrometry, the relative deviation is 0.293–0.855%, which is far lower than the requirement for the parallel samples of marine sediments, indicating that there is no obvious difference between these two methods. In addition, the DMA can use the same standard curve for at least 6 months. The DMA can more conveniently and quickly determine the total mercury in marine sediments, and can be widely popularized and used in marine sediment monitoring.