This study was purposed to investigate the B cell-activating factor belonging to the TNF family (BAFF) and a proliferation-inducing ligand (APRIL) levels in bone marrow, and the BAFF receptor expression level on B cells in multiple myeloma (MM) patients, in order to explore the characteristics of B cells in bone marrow of MM patients. MM patients were studied before treatment (newly diagnosed group, 19 patients) and after treatment with improvement (stable group, 17 patients), 10 non-hematologic patients were selected as control (control group). The BAFF receptors (BAFF-R) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) on B cell (CD19(+)), naive B cell (CD19(+)IgD(+)) and memory B cell (CD19(+)CD27(+)) of bone marrow in all groups were detected by flow cytometry. The BAFF, APRIL level in bone marrow supernatant were tested with ELISA. The results showed that the BAFF-R expression level on CD19(+) cells in newly diagnosed group were higher than that in stable group and control group; there was no significant difference between the BAFF-R expression level on CD19(+)IgD(+) cells in newly diagnosed group and stable group, but BAFF-R expression level on CD19(+)IgD(+) cells in newly diagnosed group was higher than that in control group; the BAFF-R expression level on CD19(+)CD27(+) cells in newly group was higher than that in stable group and control group; there was no significant difference between the BAFF-R expression level on CD19(+) cells, CD19(+)IgD(+) cells or CD19(+)CD27(+) cells in stable group and control group. There was no significant difference among the TACI expression level on CD19(+) cells, CD19(+)IgD(+) cells or CD19(+)CD27(+) cells in newly diagnosed group, stable group and control group. The bone marrow supernatant BAFF level in newly diagnosed group was higher than that in stable group and control group, but there was no significant difference between stable group and control group. There was no significant difference among the bone marrow TACI levels in newly diagnosed group, stable group and control group. It is concluded that both the bone marrow BAFF level and the BAFF-R expression level on CD19(+) cell, CD19(+)IgD(+) cells and CD19(+)CD27(+) cells in MM patients increase, which may help to stimulate B cells, thereby may relate with to MM pathogenesis.