Abstract: Shanganning Basin is a major Mesozoic inland basin with an area of 230000Km². There are evident differences in geothermic gradient depending on the burial depth of Mono-discontinuity. Using the relationship between temperature and vitrinite reflectance, it is possible to obtain the apparent palaeo-geothermic gradient which bears an inverse linear relation-ship to the burial depth of mohorovicic discontinuity. It is revealed that the value of vitrinite reflectance representing the maturity index of the upper palaeozoic source rock depends on the burial depth of mohorovicic discontinuity and that of the source rock itselt, and an equation for relating them has been worked out. Using multiple regression analysis for vitrinite reflectance, and the burial depth of mohorovicic discontinuity and the source rock, an empirical equation has been deduced to give the quantitative parameters for evaluating the hydrocarbon source rock of a new area and the erosional magnitude to be restored.