The invention discloses an external standard measurement method for benzene and benzene series in glyceryl triacetate by adopting headspace-gas phase mass spectrometry. Benzene and benzene series in glyceryl triacetate are determined by using a headspace-gas phase mass spectrometry method; the quantity is fixed by adopting the external standard method, in combination with optimization measures such as taking chromatographic pure glyceryl triacetate as a solvent and a matrix correction agent, and a sample pretreatment method, the detection chromatographic condition is specifically determined, relatively good chromatographic peak separation effects of benzene, methylbenzene, ethylbenzene, o-xylene, m-xylene and paraxylene are ensured, and the external standard measurement method has relatively good linear dependence. The detection limit of benzene and benzene series is 0.01-0.02mug/mL; the relative standard deviation is 1.1%-4.8%; the recovery rate is 89.9%-97.1%; the error and complicated operation caused by sample pretreatment are effectively reduced; and the treatment time is also greatly reduced.