Abstract: The essential that caused color alteration of conodonts throughout North China are the maxium palaeo-geotemperature controlled by principle tectonic framework, whereas local color alteration of conodonts in some areas was affected by factors as follows. 1) buried rock masses whichintensified the color alteration of conodonts; 2) activities of underground water which degraded the color alteration of conodonts; 3) tectonic movement which intensified the color alteration of conodonts. By analyzing the history of color alteration of conodonts from Ordovician system, it is inferred that organic matters in this sequence reached mature stage during the period from the end of Permian to the beginning of Yanshan movement. After Yanshan movement, organic matters could be transferred into petroleum secondarily within some plain areas where Cenozoic strata had deposited. The whole region of North China is then devided and evaluated in terms of maturities of organic matters.