Exhaustion of profitable coal resources makes for need of innovation including underground coal gasification ( UCG) ． One of the most important problems of UCG is evaluation of the combustion area in underground coal seams． Physicochemical parameters of coal，in a whole，and coal mineral substance are changed under heating and combusting． Thermo-chemical conversion of coal mineral components has an effect on magnetic characteristics of coal seam and can be used for real-time control of combusting area． To this guessing check laboratory experiments have been made as an activity of the Far Eastern Federal University． Our investigation based on a theoretical analysis and laboratory simulation tests． Typical results of the laboratory experiments are presented below． Under heating coal thermo-chemical magnetization is forming． Coal's magnetic parameters varieties from anti-ferromagnetiс to ferromagnetic． Anti-ferromagnetic pyrite and siderite presented into coal mass is transformed into magnetic hematite and magnetite under heating． Therefore，geomagnetic is expected to be a useful geophysical tool to for evaluation of combustion volume and its migration for underground coal gasification．