Abstract: Two kinds of theoretical geodynamic models (the uniform extension model and thenon-uniform extension model)of extensional basins were used to simulate the observed tectonic subsidence of the Songliao Basin to discuss the mechanism of extensional basins. Byfitting it with actual measured data,he genetic mechanism and evolution history of thebasin can be further recognized.Especially,the quantitive parameters of basin evolutionprocess such as extension quantity,tectonic subsidence,paleo-heat-flow,paleotemperatureand vein intrusive amount can be calculated.