Objective：To discuss the changes of the biological characteristics of bone marrow-derived mesenchymal stem cells（BMSCs） in the microenvironment of C6 glioma cells. Methods：Whole bone marrow adherent cultivation was used to isolate and culture SD rat BMSCs. Immunofluorescence（IF） was used to detect the surface makers of BMSCs（CD90+，CD105+，CD45-）. BMSCs was labeled with a fluorescent dye CM-Dil（CM-Dil+BMSCs） and the labeling efficiency was examined with flow cytometry（FCM）. The inhibitory rate of CM-Dil+BMSCs was continuously tested by trypan blue staining assay. In direct-co-culture group，CM-Dil+BMSCs was directly co-cultured with C6 glioma cells；in indirect-co-culture group，BMSCs was indirectly co-cultured with C6 glioma cells；in positive control group，C6 glioma cells was separately cultured and in negative control group，BMSCs was separately cultured. After 7 d，IF was applied to detect the expression of glial fibrillary acidic protein（GFAP） of each group. Gene expression of GFAP，PTEN，Bcl-xl，CyclinD1，CD90，CD105 of each group was detected by real time quantitative polymerase chain reaction（RT-qPCR）. Results：（1）It was showed by IF that more than 90% of the third generation of BMSCs expressed CD90，CD105，but not CD45. （2）Expression of GFAP of BMSCs in direct-co-culture group and indirect-co-culture group was increased compared with that in negative control group，while the expression of CD90 and CD105 were decreased. Gene expression of GFAP，PTEN，Bcl-xl，CyclinD1 was significantly increased in direct-co-culture group and indirect-co-culture group compared with that in negative control group（P＜0.05）. There was no difference between direct-co-culture group and indirect-co-culture group（P ＞0.05）. Gene expression of CD90，D105 was significantly decreased in direct-co-culture group and indirect-co-culture group compared with that in negative control group（P＜0.05）. Conclusion：BMSCs in the microenvironment of C6 glioma cells have the potential malignant transformation tendency.