Abstract: For the problems that trimethylamine and dimethyl ether is not effectively separated and the enrichment process for trimethylamine is more complicated when conventional capillary or packed columns were used for separation and determination of trimethylamine in dimethyl ether aerosol by gas chromatography, a new method using CP-PoraPLOT Amines column and FID detector has been developed. The new method can provide both qualitative and quantitative analytical data for trimethylamine in dimethyl ether aerosol. On-line monitoring of trimethylamine can also be realized when auto-sampling valve is used. The detection limit of the method for trimethylamine is 0.51×10^-6 (V/V) and the recovery of the method is 98%~103% with procession of 1.07% RSD (n=7). The method is suitable for online monitoring of trimethylamine in industrial production.