With the hydrous thermal pressure simulation experiments of the solid bitumen,bitumen limestone,bitumen sandstone and oil with different media,the experiment result of the characteristic of gas-generating factor,gas-generation potentiality and their affecting factor of the marine crude oil and bitumen was correlated.The experiment results indicated that the gas-generation potentiality of marine crude oil and bitumen not only related to the lithology and the evolution grade but also to the abundance and component of the soluble organism.The most hydrocarbon gas generating factor heightens with the atomic ratio of hydrogen to carbon.The reservoir rock or the rocks in migration path are the new source of light oil or natural gas when they reach to matured-high matured stages.