An amino-functionalized mesoporous bioactive glass (N-MBG) with a high drug loading capacity and longer drug release time was successfully prepared by using 3-aminopropyltriethoxysilane (APTES) in a short-time chemical reaction. The drug release performance of an MBG and the N-MBG were studied by loading gentamicin sulfate (GS) in a simulated body fluid solution. The results showed that the surface area of the N-MBG increases to 355.01 m2 g-1 after amination at 80 °C for 1 h compared with that of the MBG (288.07 m2 g-1). Meanwhile, the surface zeta-potential of the N-MBG charges from the original negative charge (-10.06 mV) to the positive charge (+5.30 mV). Furthermore, the GS loading rate of the N-MBG is up to 62.92 ± 2.02%, higher than that of the MBG (48.90 ± 1.71%). In addition, the N-MBG has a longer drug release period and the seven-day accumulative release from the N-MBG reached only 45.9 ± 1.8%, significantly lower than that of the MBG, 60.7 ± 2.3%. In vitro bioactivity tests suggested that the N-MBG exhibited good biological activity. In conclusion, the N-MBG with a higher loading capacity and longer drug release time can serve as a promising candidate as a drug carrier.