Abstract: Based on the experiments of natural kerogen pyrolysis and pyrolytic simulations,it is proposed that the ratio of 1550cm^-1/1600cm^-1 1R measured on Kerogens can be taken as a geothermometer. In kinetic analysis, it is suggested that the variation of the ratio is mainly dominated by geotemperature. Therefore, this geothemometer is well enough to reveal the influence of geotemperature above 100℃, especially the hydrothermal influence.