Abstract: By means of hydrothermal simulation,the similarities and differences of the hydrocarbon generating characteristics of algae kerogen in the media of carbonate rock and mudstone are analysed.There are small differences in the hydrocarbon compositions of liquid products,the gas chromatograms of saturated hydrocarbons and the characteristics of solid kerogen between carbonate rock and mudstone.The gas yield is obviously small in the medium of mudstone and water than in that of carbonate rock and water.The main reason is that a great amount of CO₂ are formed in the medium of carbonate rock.The catalysis of clay mineral on gaseous hydrocarbons is revealed specifically by the fact that unsaturated hydrocarbons change into saturated hydrocarbons through hydrogen addition catalysis.This is more effective for low molecular methane.The catalysis of carbonate rock to unsaturated hydrocarbons and methane is not so good as mudstone.But it is more favourable to the generation of heavier gaseous hydrocarbons.Before the time to generate a great amount of oil,the oil generating amount of carbonate rock is high than that of mudstone.At the time of oil generating peak,the total liquid products of the both are almost equal.The oil generating peak of mudstone is generally consistent with or slightly later than that of carbonate rock.