Objective To investigate expression of Nanog protein in mouse adipose-derived mesenchymal stem cells （ADMSCs). Methods ADMSCs were isolated and cultured. The ADMSCs subpopulations for CD73+ and CD73- were selected by flow cytometry and then were cultured and passaged.Immunocytochemistry and immunofluorescence were used to detect the expresssion of nanog protein and compared expression difference between two subpopulations. Results The percentage of CD73+ cell in all ADMSCs was about 5%. According to their morphology,these cells were divided into big cells and small cell. The strong positive expression rate of Nanog protein for CD73+ ADMSCs was（16.85±6.83）%, the weak positive rate was（81.78±7.19）%, and the negative positive rate was（1.63±3.59）%; The strong positive expression rate of Nanog protein for CD73- ADMSCs was（5.74±2.79）%, the weak positive rate was（85.84±37.31）%， the negative rate was（8.42±4.12）%. The different mitotic division phase of the Nanog positive cells was detected. The dividing cells of CD73+ ADMSCs were more than those