Phoma　fungi　are　known　to　produce　a　diverse　range　of　natural　products　which　possess　various　biological　activities　such　as　antifungal,　antimicrobial,　insecticidal,　cytotoxic,　and　immunomodulatory　effects.　In　our　present　study,　we　have　isolated　two　novel　polyketides　(1　and　3),　one　new　sesquiterpenoid　(2),　and　eight　known　compounds　(4–11)　from　the　culture　of　Phoma　sp.　3A00413,　a　deep-sea　sulphide-derived　fungus.　The　structures　of　compounds　1–3　were　elucidated　using　NMR,　MS,　NMR　calculation,　and　ECD　calculation.　In　vitro　antibacterial　activities　of　all　the　isolated　compounds　were　evaluated　against　Escherichia　coli,　Vibrio　parahaemolyticus　vp-HL,　Vibrio　parahaemolyticus,　Staphylococcus　aureus,　Vibrio　vulnificus,　and　Salmonella　enteritidis.　Compounds　1,　7,　and　8　exhibited　weak　inhibition　against　Staphylococcus　aureus　growth,　while　compounds　3　and　7　showed　weak　inhibition　against　Vibrio　vulnificus　growth.　Importantly,　compound　3　demonstrated　exceptional　potency　against　Vibrio　parahaemolyticus,　with　a　minimum　inhibitory　concentration　(MIC)　of　3.1　μM.　©　2023