Objective：To induce the RAW264.7 and human blood CD14+ cells to differentiate into osteoclasts，to detect the transcrip－tion and expression of the osteoclast during its differentiation and maturation，and define the expressing position of Na+-H+ antiporter 2. Methods：The RAW264.7 and human blood CD14+ cells were induced to differentiate into osteoclasts by RANKL and M-CSF in vitro；the transcription of NHA2 was detected by RT-PCR during induction；the antiporter expression was tested by Western blot be－fore and after induction，and the exact position of its expression was defined by immunocytochemistry. Results：The RAW264.7 and human blood CD14+ cells were differentiated into osteoclasts by RANKL and M-CSF；the RT-PCR result indicated the transcription level was increased during osteoclast differentiation and maturation；the Western blot test revealed the antiporter was only expressed in the maturated osteoclast；and the immunocytochemistry experiment told us that the antiporter was mainly expressed in the mito－chondria of osteoclast. Conclusion：Na+-H+ Antiporter 2 was mainly expressed in the mitochondria of maturated osteoclast as a salt antiporter，which will affect the development and differentiation of osteoclast through controlling the metabolized balance of mitochon－dria.