Objective To investigate the effects of myeloid-related protein 8 (MRP8), MRP14 and MRP8/14 heterodimer on the phenotypic maturation of mice bone marrow-derived dendritic cells (BMDCs). Methods BMDCs were cultured and purified in vitro and divided into control group (equal volume of PBS), MRP14 (1 μg/mL) treatment group, MRP8 (1 μg/mL) treatment group and MRP8/14 (1 μg/mL) treatment group. Flow cytometry was used to detect the expression of costimulatory molecules, such as CD40, CD80, CD86 and major histocompatibility complex II (MHC II ) on the surface of BMDCs after stimulation. Results MRP14, MRP8 and MRP8/14 promoted the expression of CD40, CD80 and CD86, while MRP14 and MRP8 promoted the expression of MHC II on the surface of BMDCs. Moreover, the ability to promote the expression of CD80 and CD86 is stronger in MRP14 and MRP8/14 than MRP8. Conclusion MRP14, MRP8 and MRP8/14 promote the phenotypic maturation of BMDCs by increasing the expression of costimulatory molecules, and MRP14, MRP8 and MRP8/14 also differ in their ability to promote BMDCs to expresse various costimulatory molecules.