Inner Mongolia has complex gravity anomalies. The Da Hinggan Mountain in the east of Inner

Mongolia is a mirror-image anomaly area. There exist low gravity of rock body, high gravity of Sungliao

Plain, mountain root and anti-root, and the AREM model is tenable. The Yinshan mountain chain in

the middle of Inner Mongolia is a mountain anomaly area. There exists high gravity of rock body, but

mountain root effect on the gentle Moho surface is nonexistent, and the Pratt model is tenable. Low-

gravity anomaly of the Dadong Mountain occurs in the middle of the mountain anomaly area.

Comparative studies suggest that the low-gravity anomaly of the Dadong Mountain is neither a

mountain anomaly nor a mirror-image anomaly, but a rock body anomaly. The isostatic compensation

occurs in the lower boundary of the intracrustal granitic layer. It can be said that, in addition to the

mountain anomaly and mirror-image anomaly, there is also a granite anomaly.