According to the results of physical geography detecting on Changbaishan Volcno region,There is low velocity structure  related with high temperature substance or magma chamber at the depth 8-10km under the ground.We computed the sensitivity region of ground deformation in Changbaishan Volcano Using elastic theory sphere sorce model developed by Mogi in 1985, and found the sensitivity region is 5.6-7km apart from the crater.This conclusion will provide evidence to set the Changbaishan Volcno GNSS net.