Abstract: In this study, the effect of sargasso fucosan sulfate ( SF) with different components on inhibition of human lung cancer A549 cells was studied. The effect of different cell counts in the planking and SF with different concentrations on cell growth curve was detected according to the MTT assay; the proliferation inhibition rate of SF with different components on this cell at different times; the effect of SF on morphology of this cell was observed under an inverted microscope.The results showed that, when concentration of SF was set in the range of 1²5mg /mL, cell count in the planking was 5 × 103cell /mL, the cell growth curve had a good linearity; SF with different components all had inhibitory effect on human lung cancer A549 cells, in which SF2-R had the strongest inhibitory effect on the cells, and the inhibition rate was 61.06%.