Carbon circulation is a very important subject in recent studies of the env ironmental geology. It is pointed out in this paper that there existed strong ge othermal ac tivity with a lot of hot springs controlled by deep faults around the Tianchi L a k e, Changbai Mountains, and the plentiful CO2 outgassed from the h ots prings meanly came from the upper mantle. Also the CO2 had a connection with t he thrust and flow in the upper mantle.