Objective To stimulate a human monocytic cell line THP-1 cells to differentiate into M1, M2 macrophages and dendritic (DC) cells by optimization of different methods, and lay the foundation for the study of M1, M2 and DC cell models in vitro. Methods THP-1 cells were stimulated by PMA and GM-CSF/M-CSF, respectively. Then, they were induced to differentiate into M1, M2 macrophages and DC cells by adding different cytokines, such as LPS, IL-6 and IFN-γ for M1 macrophages, IL-4, IL-13 and IL-6 for M2 macrophages, and IL-4 for DCs. Subsequently, the morphology of cells was observed and the expression of cell surface (CD) molecules was detected by flow cytometry. Results After stimulation with the two methods, the trends of CD molecules expression were basically the same. The expression of CD80 and CD86 on the THP-1-M1 cells were increased significantly, and CD163 and CD209 were highly expressed on the THP-1-M2 cells. For THP-1-DC cells, the expression of CD14 was significantly decreased, while the expression of CD80, CD86 and CD11c increased. M1, M2 macrophages and DC cells were adherent after stimulation with PMA. However, DC cells were partially adherent after GM-CSF/M-CSF treatment. M1 and M2 macrophages were also growing in suspension. Conclusions Both methods used in this study can successfully induce THP-1 cells to differentiate into different subtypes, but there are some differences in the morphology of the induced cells. Appropriate stimulation method can be selected according to the experimental requirements.