Abstract: The colour of fossil sporo-pollen is increasingly altered from light to dark with burial depth, pressure and temperature, when the temperature reaches a critical point, original organic matter is transfered into petro leum. Therefore, by means of the colourity of fossil sporo-pollen, the organic alteration stage can be inferred. In Dongpu Depression, on the basis of our research, a conclusion has been reached as follows, For yellow section, underground temperature is 65-93℃, the colour alteration indicates an immature stage. For brown section, 93-125℃, the colour alteration indicates a mature stage. For dark brown section, 125-151℃, the colour alteration indicates a highly-mature stage. For brown-black section, the underground temperature exceeds 151℃, the colour alteration indicates a supermature stage. The study of the colour alteration of fossil sporo-pollen is an important tool for inferring. The evolution of organic matter provides basic information for oil and gas exploration. For this reason, the colour alteration of fossil sporo-pollen can be taken as an indicator of petroleum generation.