研究红藻海头红(Plocamium telfairiae Harv.)的化学成分，分析其抗菌活性来源。通过硅胶柱色谱、Sephadex LH-20凝胶柱色谱和薄层色谱对海头红乙醇提取物的抗菌成分进行活性追踪分离，并通过质谱和波普数据分析鉴定化合物的结构。在分离过程中得到4种化合物，通过GC-MS、1H-NMR和13C-NMR对化合物进行分析鉴定，经鉴定4种化合物分别为十六烷酸、十八烷酸、对羟基苯甲酸、邻苯二甲酸二辛脂，对羟基苯甲酸为海头红乙醇提取物中的一种抗菌化合物。

To study the chemical constituents and antimicrobial compounds of Plocamium telfairiae Harv., the silica gel column, SephadexLH-20 column and thin layer chromatographic techniques were applied to separate and purify the compounds. structures of compounds were confirmed by the data of mass spectrum and spectral. Four compounds were isolated from the ethanol extract of Plocamium telfairiae Harv.. Then these compounds were identified by GC-MS, 1H-NMR and 13C-NMR spectral analysis. Four compounds were identified as n-hexadecanoic acid, octadecanoic acid, 4-hydroxybenzoic acid, dioctyl phthalate. The 4-hydroxybenzoic acid was an antimicrobial compounds from ethanol extract of Plocamium telfairiae Harv..