The invention discloses a method for discriminating the truth of fermented beef ham through detecting the compositions of a flavor substance by a gas chromatography-smelling method/a gas chromatography-mass spectrometry method. The method comprises the following steps: when a sample of a flavor substance of fermented beef ham to be detected is prepared through dynamic headspace purging and trapping, the suitable purging time of nitrogen gas is 30 minutes; when the flavor substance is detected by utilizing the gas chromatography-mass spectrometry method, the fermented beef ham contains fifteen flavor substance compositions: namely, 2-propylene-1-mercaptan, dimethyl benzene methanol, 3-methyl butyraldehyde, benzaldehyde, methyl-5-heptene-2-ketones, acetophenone, alpha-pinene, beta-pinene, styrene, dipentene, biphenyl, naphthalene, 2-methyl naphthalene, phenol, eucalyptus essential oil and anethole; and when the compositions of the smelling flavor substance are detected by the chromatography-smelling method, the fermented beef ham contains trimethyl butyraldehyde, benzaldehyde, dimethyl disulfide, naphthalene, alpha-pinene and benzothiazole. The method can be widely applied to quality detection and discrimination; and the process design, improvement and management of the fermented beef ham.