Abstract: In the light of the theory of origin,migration and accumulation of oil and gas,integrated with geology,geophysics,geochemistry and mathematical geology,and in reference to the advanced method of evaluation applied at home and abroad and our experiences gained from offshore basins,a rather comprehensive method and diagram for estimating hydrocarbon resources has bee.worked out,including evaluation of regional geology and of conditions pertaining to the trapping and generation of hydrocarbons as well as the reservoir and cap rocks.