Abstract: Scientific evidence in drug-driving cases and its analysis methods play an important roles in traffic-related legislation and legal justice. The method of gas chromatography-positive chemical ionization-tandem mass spectrometer (GC-PCI-MS/MS) was utilized in sample preparation and analysis process, in order to detect the amphetamines in trace and decayed blood samples. 370 blood sample residues were collected from traffic accident cases and tested for blood alcohol concentration (BAC)， which were re-tested for amphetamines. The results indicate that the method has low limits of detection (LODs) for four amphetamines, show a good linearity and high extraction recoveries. Approximately 0.27% of the blood sample residues are positive for amphetamines. The results provide an efficient method for drug-driving cases as well as important data for the related legislation.