Abstract: Based on age study of apatite fission track of Carbonif-erous in Bayanhaote basin,it is believed that the annealing age was after Jurassic and Jurassic had not experienced tem-peratures over120℃ever since then while Carboniferous largely reached the highest annealing temperature of apatite at the end of Cretaceous.The paleo -geotemperature that Carboniferous went through at geologic history could not be too high and commonly was under120℃.The highest geotemperature occurred at late Cretaceous when large amount of organic materials began to generate hydrocarbons.It has the characteristics of late hydrocarbon generation.