Abstract: Base on the fundamental concept of the field theory,this paper states the characteristics of the geochemical field in brief,discusses emphatically the evolution and characteristics of the geochemical field during hydrocarbon formation,and probes into the coupling actions between the organic geochemical field and other geologic fields(such as the geothermal field,the stress field,etc.)during hydrocarbon formation.It is considered that the mutual matching of different fields is the key factor for the formation of petroleum accumulation.