With the continuous strengthening of environmental pollution control in China, trichloroacetaldehyde is a priority monitoring pollutant in China's environment. It can slowly evaporate in the air, has a strong spicy pungent odor, and has strong toxicity. Its detection is of great significance. Gas chromatography can be used to determine trichloroacetaldehyde in water. This method has the advantages of simple and rapid method, less sampling, less interference and low detection limit. It can meet the requirements of trichloroethylene in water such as agricultural irrigation and drinking water. Determination of acetaldehyde requirements. Method required instruments: gas chromatograph; electron capture detector: radioactive source Ni63; column: 10% silicone oil (I) / 101 pickling white carrier, inner diameter 4mm, length 2m stainless steel column. The preparation and aging method of the column: the 101 white support was soaked in hydrochloric acid for 24 hours and then washed with deionized water, and then 9.9 g of the support was weighed, poured into a solution of 1.1 g of silicone oil (I), and stirred uniformly. After the natural evaporation to dry, the desired 10% silicone oil (I) / 101 pickling white carrier stationary phase was obtained, placed in an infrared drying oven for drying for 0.5 h, taken out and cooled to room temperature for use. The treated stationary phase was loaded into a stainless steel column with a vacuum pump, and both ends were packed with fiber cotton to complete the preparation of the desired column. Connect it to the gas chromatograph, pass nitrogen (flow rate 30mL / min, column temperature 110 ° C) for 5 ~ 6h, after the baseline is stable, the aging of the column is completed. Chromatographic conditions: pulse interval 25 μs, carrier gas flow rate 60 mL/min, inlet temperature 95 ° C, detector temperature 140 ° C, column temperature 100 ° C. Test method: the water sample is first extracted with petroleum ether, the high boiling point compound is removed, the sodium chloride is added to the emulsion, and then extracted with petroleum ether-*** mixed solvent (volume fraction of 2) three times, and the extract is separated by chromatography. , detected by an electron capture detector.