Abstract: A bubbling absorber was used for the collection and enrichment of unsymmetrical dimethylhydrazine (UDMH) in air with mixed solution of salicylaldehyde and water (1+50) as absorbent.The absorbed analyte in absorbent were derivatized with salicylaldehyde at 50 ℃ for 3 h,and analyzed by GC-MS.It was found that when the sampling flow rate was 0.2 L·min-1,the absorption efficiency of UDMH achieved to 95%-98%.Linear relationship between values of peak area and mass concentration of UDMH was obtained in the range within 40.0 mg·L-1,with detection limit (3S/N) of 0.878 mg·L-1.Tests for precision and recovery were made by standard addition method,giving RSD′s (n=6) in the range of 2.96%-4.09% and values of recovery in the range of 88.0%-93.0%.