Morphine, codeine and 6-acetyl morphine in human blood was detected using solid-phase extraction and gas chromatography/mass spectrometry-selected ion monitoring, with ethyl morphine as internal standard, 3 opiates spiked in blank blood were extracted using a solid-phase cartridge. The fluent was evaporated to dryness followed by being derivatized with MBTFA, then it was analyzed directly by GC/MS in selected ion mode. The method was validated in the range 10~1000ng/mL with the drug-spiked blood, the reactor responded linearly over the studied range (R²>0.99 for the 3 drugs); The relative standard deviations (RSD) for intra and inter-days were less than10% and 16%, respectively the relative extraction recoveries vary from 79% to 116%, and LODs were less than 1, 0.5 and 3ng/mL, which promised the perspective application of the method in detecting trace amount of opium in human blood.