It was clearly demonstrated that the silver stainability of NORs during interphase and metaphase could be inhibited by low doses of AMD concentration. It showed that the AMD concentration could reflect the rDNA transcriptional activity in NORs. In this experiment we used HABM image analysis system to measure the variation of silver stainability of NORs treated by different doses of AMD in order to find the correlation between the rDNA transcriptional activity and the AMD concentration. The data resulted from this experiment were analysed with variance and correlation analysis method. The result showed that the variability of Ag-Nucleoli was significant in different AMD concentration and it was positively correlated with AMD concentration. So, we considered that the size of Ag-Nucleoli is one of the most precise signs when measuring the rDNA transcriptional activity with silver staining method.