Abstract: OBJECTIVE To prepare carrier gemcitabine(GemC) mesoporous silica nanoparticles(MSN) and investigate its anti-tumor activities in vitro and in vivo. METHODS Polymerization method was applied to prepare GemC-MSN. Laser particle size analyzer was used to detect the particle size distribution and Zeta potential of nanoparticles. Morphology characterization of nanoparticles was analyzed by the transmission electron microscopy. And UV was applied to evaluate the drug loading, encapsulation efficiency and in vitro release rate. MTT staining was applied to study the cytotoxicity of GemC-MSN on A549 cells. RESULTS The nanoparticles were evenly distributed. The average particle diameter was 107.29 nm (PDI 0.167), and Zeta potential was 0.107 mV. The drug loading and encapsulation efficiency were (37.31±1.25)% and (87.37±2.12)%, individually. The in vitro release trial revealed that drug sustainedly released from the nanoparticles, reaching the balance within 96 h. Both of the in vitro and in vivo anti-tumor activities studies showed that GemC-MSN had a stronger anti-tumor activity than free GemC. CONCLUSION As a new carrier of drug, MSN displays the good biocompatibility. It can significantly improve the drug loading of GemC and control the release at a relative slow rate, increasing the anti-tumor activity of GemC in vitro and in vivo. This study can provide a reference for the futher investigation of GemC new drug delivery systems.