The compositions and contents of amino acids and fatty acids of Enteromorpha prolifera were determined by automatic amino acid analyzer and gas chromatograph mass spectrometry (GC+MS). Eighteen amino acids were found in the samples and total amino acids (TAA) was 8.78％. Human essential amino acids (TAA) covered 35.08％ of the total amino acid. Among the 19 kinds of fatty acids of C12～C24, the content of total unsaturated fatty acid was 65.78％, which were mainly high polyunsaturated fatty acid with a high percentage of C12 and C24. The content of ω-3 unsaturated fatty acid was 29.68％ of all fatty acids, and the content of characteristic fatty acid of chloraphyta—all cis 6,9,12 Octadecatrienoic was 18.70%.