This study was aimed to investigate the effects of different stimulatory factors on proliferation and function of cytokine induced killer (CIK) cells. Peripheral blood mononuclear cells (PBMNC) were separated by Ficoll-Hypacue gradient. According to supplement of different stimulatory factors (CD28 mAb, IL-15 and IL-21), the experiment was divided into five groups:control group (CIK), CB28+IL-15+IL-21 group, IL-15+IL-21 group, CD28+IL-15 group and CD28+IL-21 group. Effects of different stimulatory factors on the proliferation of CIK cells were assayed by an automated hematology analyzer. Changes of granzyme B,perforin and CD107a were detected by flow cytometry. IL-10, IL-12, INF-γ and TNF-α were quantified by ELISA. Cytotoxicities on lung cancer cell line A549, breast adenocarcinoma cell line MFC-7 and human melanoma cell line HME1 were examined by lactate dehydrogenase release method. The results showed that there were significant differences among different groups. The highest proliferation index on days 10 was observed in group CD28mAb, IL-15 and IL-21(255.3 ± 6.3), which was higher than control group, IL-21+IL-15 group and CD28 mAb+IL-21 group (166.6 ± 13.5, 199.4 ± 15.0 and 228.8 ± 16.6) (P < 0.05). The expression of perforin in CD28 mAb+IL-15 group was higher than the other groups. The expression of perforin,GranB and CD107a of costimulatory groups was higher than control group. The cytotoxicities of CD28 mAb+IL-15 group on A549, MFC-7 and HME1 cells (82.2%, 59.3% and 70.6%) were much higher than that of control group (60.9%, 49.6% and 48.4%) (P < 0.05). The highest IFN-γsecretion was found in CD28 mAb, IL-15 and IL-21 groups. It is concluded that there are significant difference of proliferative capacity, cytokine secretion and cytotoxicity after being activated by different stimulatory factors. Adding corresponding stimulatory factors into the culture system displays a great value for target cells culture.