Abstract: The article determines the heroin metabolites in urine by using the solid phase membrane extractor and GC/MS Large-Volume injection method. The recovery , linearity, and minimum detection level of morphine and monoactylmorphine were determined. The recoveries of morphine and monoactylmorphine were more than 80%; the minimum detection levels of them were below 0.01ug/ml; good linearity for both morphine and monoactylmorphine were obtained between 0.02~50ug. One urine specimens of heroin abuse were determined successfully by using this method.