Abstract: A method of head-space GC for the determination of residual amount of monomer (MMA) of polymethylmethacrylate (PMMA) in its products was proposed. The equilibrium temperature and time of head space were set at 90 ℃ and 30 min,respectively. The PMMA sample was dissolved in N,N-dimethylacetamide, and the analyte was separated on HP-INNOWAX column and detected by FID. Linear relationship between values of peak area and mass concentration of MMA was kept in the range of 1.00-250 mg·L-1 with detection limit (3S/N) of 2.5 mg·kg-1. Tests for recovery were performed by addition of methyl methacrylate standard at 3 concentration levels, results of recovery found were in the range of 89.0%-101% with RSD′s (n=6) less than 2.5%.