Abstract: A method for determination of common drugs and metabolites in hair by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) with ultrasonic extraction was established. Hair sample of 40-60 mg was dried after washing by water, dichlorocarbon and acetone. The hair sample was cut into 1 mm segments, and 6 broken beads of 3.2 mm were added. The sample was broken cryogenically for 5 min. Then methanol of 1 mL was added into broken hair sample of 20 mg, and ultrasonic extraction was carried out at 0℃ for 20 min in an ice-water bath. The supernatant was filtered by 0.25 μm organic filter membrane and determined by UHPLC-MS/MS. It was showed that linear relationships between mass fractions of O⁶-monoacetylmorphine (6-AM), morphine (MOR), ketamine, methamphetamine (MAMP), amphetamine (AMP), cocaine (COC), benzoyl-iconine (BZE), 3,4-methylene dioxymethamphetamine (MDMA), 3,4-methylene dioxyamphetamine (MDA), 3,4-methylene dioxyethyl amphetamine (MDEA), codeine (COD), normethylene ketamine (NK), tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN) and their peak areas were kept in definite ranges, with detection limits (3S/N) of 0.001 ng·mg^-1 for BZE, THC, CBD, COC, CBN, and 0.004 ng·mg^-1 for 6-AM, MOR, ketamine, MAMP, AMP, MDMA, MDA, MDEA, COD, NK. Recovery test was made on blank samples at 3 concentration levels by standard addition method, giving results in the range of 73.3%-97.8%, and RSDs (n=10) of the determined values were ranged from 4.3% to 14%. This method has been used to test substantial samples, and the results were consistent with those of standards of forensic science.