Abstract: Through hydrolysis of soy lecityin,the phosphatidyl inositol produced was acetylated with acetyl anhydride to give inositol hexacetate,which was then determined by gas chromatography.Amount of phosphatidyl inositol contained in the sample was calculated indirectly from the amount of inositol hexacetate found by GC.Six portions of a soy lecithin sample were taken and its phosphatidyl inositol content were determined by the proposed method,giving an average value of 8.61 mg·g-1 with a value of RSD (n=6) 2.2%.Test for recovery was made by adding different amounts of standard phosphatidyl inositol from 10.0 mg to 110.0 mg,values of recovery found were in the range of 95.6%-104.2%.