Via investigating typical Palaeozoic and Mesozoic petroleum-bearing basins in China by using thermal maturation theories of organic matter to improve the conventional Karweil’s method, a new method to reconstruct hydrocarbon-generating histories of source rocks has been suggested. This method, combining geological background with geochemical information makes the calculated VRo closer to the measured one. Moreover, it enables us to make clear the hydrocarbon generation trend of source rocks during geological history. The method has the merits of simple calculation and objective presentation, especially suitable to basins whose sedimentation and tectonic movements are complicated. Via investigating typical Palaeozoic and Mesozoic petroleum-bearing basins in China by using thermal maturation theories of organic matter to improve the conventional Karweil’s method, a new method to reconstruct hydrocarbon-generating histories of source rocks has been suggested. This method, combining geological background with geochemical information makes the calculated VRo closer to the measured one. Moreover, it enables us to make clear the hydrocarbon generation trend of source rocks during geological history. The method has the merits of simple calculation and objective presentation, especially suitable to basins whose sedimentation and tectonic movements are complicated.