Abstract: Production of bean sprout has the centuries-old history in China.Bean sprout has high nutritional value，and is a very popular food.But recently，some producers added the hormones plant growth regulator in the production of bean sprout to shorten growth time and make it tender，white and thick，and 2，4-D is one kind of these growth regulators.Existing test methods were improved，2，4-D in bean sprout was distilled with methyl cyanide，derived with 14% boron trifluoride formaldehyde solvent，extracted with hexane，and detected by gas chromatography with HP-5 quartz capillary column and ECD detector.This determination could detect 2，4-D quantity in bean sprout more conveniently，rapidly and exactly.Results proved that this determination has good linearity response，correlative coefficient was between 0.995 and 1.000，detection limit was 0.002 mgkg，and recovery for spiked standards was between 91% and 103%.