Since cART was introduced to treat AIDS, the mortality rate due to AIDS has markedly decreased and the convalescence of HIV-infected individuals has improved drastically. However, HIV-1 sexual transmission has made HIV become a global epidemic. Sacran is a megamolecular poly-saccharide extracted from cyanobacterium Aphanothece sacrum that exhibits numerous desirable characteristics for transdermic applications, such as safety as a biomaterial, a high moisture re-tention effect, the ability to form a film and hydrogel, and an anti-inflammatory effect. In this study, we evaluated the anti-HIV-1 effects of Sacran as a barrier to HIV transmission. Sacran inhibited HIV-1 infection and envelope-dependent cell-to-cell fusion. Moreover, we used a Transwell assay to confirm that sacran inhibited viral diffusion and captured viruses. The synergistic effects of sacran and other anti-HIV infection drugs were also evaluated.HIV-1 infections can be reduced through the synergistic effects of sacran and anti-HIV-1 drugs. Our study suggests the use of sacran gel to protect against HIV-1 transmission.