Abstract: Both all methods to study the thermal maturity of the organic matter in hydrocarbon source rocks and their practical problems are presented in detail. Some conclusions are reached as following:The thermal maturity indicators of insoluable organic matter are more importent than others from the analysis of the soluable matter,light hydrocarbon and mineral. Moreover,theway of laser induced fluorescence of the aro- matics has found special significance in determination of the thermal maturity of oil and marine sourse rocks of high maturity stage. Howerer, to determine correctly the thermal maturity of source rocks in some regions, not only must some indicators be used, but also some geological settings must be considered.