In targeting delivery system research on salvianolic acid B, it’s vital but hard to evaluate the tissue distribution for its low concentrations in tissues. So the simple, rapid, selective and sensitive UPLC-MS/MS method was provided hereby to determine the concentration of salvianolic acid B in mice tissues after intravenous administration of salvianolic acid B injections, conventional liposomes and long-circulating liposomes. The UPLC was conducted by a C18 column with a gradient mobile phase consisting of acetonitrile and water containing 0.1% formic acid. The tandem mass spectrometry was operated in negative-electrospray ionization selected-reaction-monitoring mode, and the optimized characteristic precursor to product ion transition m/z 717.3 [right wards] 519.1 was selected. The biosamples were homogenized and treated with a protein precipitation, which led to an acceptable matrix effect and extraction recovery. The linear calibration curves were plotted in the given concentration ranges. The intra-day and inter-day precisions were less than 13.9% and the accuracies were in the range of 86.3-109.2%. The tissue distribution results determined by UPLC-MS/MS we developed showed that the conventional and long-circulating liposomes we made had succeeded in prolonging the retention time and increasing the level of salvianolic acid B in certain distribution tissues such as liver, kidney and brain