In this paper, mercury vapor survey was employed to detect or judge the location and the grave robbery situation of the Spring-Autumn Tomb in Hancheng City. In the burial ground and peripheral section, a variety of methods of mercury vapor survey were carried out for mercury in air, mercury in soil gas and thermal-release mercury of soil in different parts of the grave. The high concentration mercury anomalies were delineated. This paper demonstrates that the shape and area of the distribution of mercury anomalies delineated by mercury vapor survey can be used to find the location of the tomb and the place of the cave dug by tomb-robbers.