Abstract: As the substitutes of cannabis, synthetic cannabinoids are widely abused as the typical category of the 3^rd abused drugs, which has aroused widespread concern of the society. The harm of abusing of synthetic cannabinoids are increasing day by day. In this paper, an approach for the simultaneous analysis of new psychoactive substances in hair by liquid chromatography-electrospray ion trap mass spectrometry has been established and applied to the qualitative and quantitative analysis of 6 synthetic cannabinoids, including JWH-073, MAM-2201, JWH-015, JWH-203, JWH-018 and JWH-007. The hair sample was cut and cleaned, and then ultrasonic extracted with methanol. Linear calibration curves showed a good linearity in the range 3~200 ng/mg, with coefficients of greater than 0.990 1, the limit of quantification was less than 3 ng/mg, the limit of detection was less than 1 ng/mg, the precisions were less than 9.99%, and the recoveries from spiked hair samples varied from 90.69% to 97.88%. The experimental results showed that the analytical strategy could provide scientific basis and evidence support for the identification, detection and litigation of drug-related cases.