A method for the determination of desmopressin in urine by liquid chromatography-tandem mass spectrometry was established.The sample was purified by Waters C18 solid phase extraction，and separated on a Phenomenx Onyx C18 chromatographic column.The analysis on the target compound was performed by MS in positive ion ionization under multiple reaction monitoring（MRM） mode.Total of eight volunteers were invited to reserve their urine samples within 3 d after each took a single-dose of desmopressin.The samples were detected by the established method and the metabolic curves for the analyte were drawn out.Results showed that the limits of detection of the method were 02 μg/L.There were linearities for desmopressin in the range of 05-20 μg/L with correlation coefficients（r2） larger than 0997.The recoveries at three spiked levels of low，medium and high concentrations were all higher than 59%，with the intra day and inter day precisions all less than 10%，and the matrix effects within 20%.The peak concentrations of desmopressin in eight volunteers occurred within 70-150 min after taking the drug，and the highest concentrations were in the range of 02-24 μg/L.The longest detection window period could last for about 13 h.This method is unique for the detection of desmopressin in urine，and fully meets the requirements of the World Anti doping Agency for 2 μg/L concentration of the drug by reducing the experiment time and the experimental cost.This method was used to analyze the positive urine after taking the drug，and the elimination of desmopressin in the human body was also investigated.