Taking the Fushun Basin as an example, this paper analyses the relation of coal metamorphism to the normal geothermal field and additional geothermal field, and establishes the thermodynamical model for the paleogeothermal field and corresponding coal metamorphism of the Basin. The 2-D simulation of the superimposition of coal geothermal metamorphism and telemagmatic thermal metamorphism has also been preliminarily accomplished. The computer simulation results have shown that the coal, formed in the Paleogene, in the Fushun Basin had an R-o,R-m value of only 0.3 +/- and the intrusion of diabase sills in the Later Oligocene increased the coal rank to the low metamorphism stage (R-o,R-m = 0.5-1.0%). It has been found in the simulation, that the way in which the thermal flow in basement rock is controlled using the results from paleogeothermal structural analysis is obviously better than the method in which a value is artificially selected for the thermal flow according to the basin basement. In addition, the former can be used to study the variation of R-o,R-m itself, so it is also better than the method to perform back-confining analysis using R-o,R-m values. (C) 2000 Elsevier Science B.V. All rights reserved.