Ancient human bones in Xigongqiao Site, Tengzhou, Shandong Province, were analyzed by use of SEM-EDS. SEM indicated that the microstructure of Haversian system was destroyed under the impact of bone diagenesis. The apparent difference in elemental distribution in the bone cross section showed that the enrichment or loss of elements can occur not only in the inner and outer surface, but also in the middle. This study will have great influence on how to deal with the ancient human bones before any palaeodietary research in the future.