The method of determining the content of diethylene glycol was established by gas chromatography adopting the HP-INNOWAX capillary column and the hydrogen flame ionization detector. It was quantitatived by the external standard method with temperature program. It maintained good linear relationship in range of 10 ~10 000 μg/mL concentration for diethylene glycol （ r =0.999 9 ） and the average recovery rate was 92.8% （ RSD=0.32%, n =9 ）. The sample was extracted with 30 mL ethanol in ultrasonic device at 35 ℃ for 30 min. The supernatant was treated with 0.45 μm organic membrane filtration and then analyzed directly by gas chromatography. 23 Brands of toothpaste were determined using this method and the results showed that it could quantitate diethylene glycol accurately, possess the characteristics of wide linear range, simple operation and practicability. It had a certain realistic directive significance to prevent the diethylene glycol in toothpaste.