Objective：To investigate the effects of proteasome inhibitor PS-341（Bortezomib） on the expression of interleukin-6（IL-6），interleukin-1β（IL-1β） and stem cell factor（SCF） and the apoptosis of U266 cells. Methods：U266 Cells were incubated with RPMI1640 and exposed to 0，50，100，150，200 nmol／L of PS-341 for 4 h, respectively. Then the apoptosis of cells was analyzed by fluorescence microscope and flow cytometry（FCM） with Annexin V-FITC／PI double staining, and the expression of IL-6，IL-1β and SCF was detected by RT-PCR. Results：Fluorescence microscope and FCM showed that PS-341 induced U266 cells apoptosis in a dose-dependent manner; The expression of IL-6, IL-1β and SCF was decreased significantly after PS-341 treatment. The inhibitory effect on IL-6 and SCF was positively related with drug concentration. The expression of IL-1β was decreased gradually when the drug concentration was increased from 0 nmol／L to 150 nmol／L, whereas the expression level of IL-1β remained unchangeable when the drug concentration exceeded 150 nmol／L. Conclusion：Proteasome inhibitor PS-341 could significantly downregulate the expressions of IL-6，IL-1β and SCF in U266 cells, which might be one of the mechanisms for PS-341 for treatment of multiple myeloma.