The adsorption of vitamin B3 (VPP) by activated carbons and their release processes in the distilled water, simulated gastric fluid and simulated intestinal fluid were investigated. The adsorptive capacity of the activated carbon for VPP was 94.91 mg/g. Simulated gastric fluid could promote the release of VPP adsorbed by the activated carbon, and the cumulative percentage of VPP released was 76.36%. Based on three commonly-used kinetic models for drug release, mathematical simulations were carried out. It was found that the release processes of VPP in three different media could be fitted well by the Higuchi model Q = kt1/2 + C.