Alternaria toxins are widespread food contaminants， accompanying with alternariol(AOH)， alternariol monomethyl ether (AME)， tenuazonic acid (TeA)， and Tentoxin (TEN). Currently， there is limited assessment on their combined toxicity. Objective: To evaluate the combined toxicity of four common alternaria toxins on liver cells using BRL-3A cells as a research model. Methods: A CCK-8 kit was applied to detect changes in cell viability of BRL-3A cells treated with 10-200 μmol/L alternaria toxin alone or in combination for 24， 48， 72 h. Based on the combination index method， the combined toxicity after their mixed exposure were analyzed. Results: When the BRL-3A cells were treated with AOH， AME， TeA and TEN alone， the cell survival rate was reduced in a dose- and time-dependent manner. Their IC50 were 38.11， 41.25， 49.05， 358.58 μmol/L(48 h)， respectively. Moreover， the toxicity of AOH-AME， AME-TEN and TeA-TEN combinations all showed additive or synergistic effects at IC10-IC90 levels. The toxicity of the AOH-AME-TeA， AME-TeA-TEN and AOH-AME-TeA-TEN combination showed antagonistic effects at low doses and synergistic effects at high doses， while the other combinations showed the opposite results. Conclusion: All four alternaria toxins in food inhibit the proliferation of BRL-3A cells in varying degrees， with toxicity intensity being AOH > AME > TeA >> TEN. When coexist， a synergistic effect occurs in their toxicity effect， suggests that we need to focus on the combined toxicity risk of toxins in order to assess their safety risk more accurately in the future.