Abstract: An in-vitro digestion method was used to investigate the effect of boiling and dried-rehydration treatments on total concentration and bioaccessibility of four elements(Pb,Cd,Se,Zn)in seaweed. Contents were determined by ICP-MS. The contents of Zn and Cd in two thermal treatments samples were significantly higher than those in the raw seaweed(p<0.05),while Pb had the opposite trends. The bioaccessibility of Pb,Cd,Se,Zn were 39.28%~105.88%,34.88%~55.32%,86.24%~97.67% and 59.35%~98.76% before and after cooking,respectively. The bioaccessibility of Pb and Cd decreased in seaweed cooked by both thermal processes. While the bioaccessibility of Zn increased after cooking. By contrast,the bioaccessibility of four metals treated by dried-rehydration were basically higher than those by boiling treatment. A significant correlation was observed between the concentration and bioaccessibility of elements except the bioaccessibility of Cd and Zn(p<0.05). The utilization of four elements in seaweed was closely related to the thermal processes.