Abstract: This paper describes the significance of C₁-C₁₄ light hydrocarbons in quantitatve evaluation of source beds and briefly introduces the principles and analytical procedures of pyrolytical GC. According to the data from pyrolytical analyses of three types of kerogens, it is proposed the compen-sation coefficients of light hydrocarbons for the evaluation of source bed, i.e.the compensation coefficients of light hydrocarbons for the overall conversion efficiency of kerogens or organic carbon are as follows. During immature stage, 37.69-76.93% for Type I kerogen, 7.74-11.02% for Type Ⅱ kerogen and 32.66-34.72% for Type Ⅲ kerogen. In mature stage, 19.16-23.70% for Type Ⅰ kerogen, 12.27-13.72% for Type Ⅱ kerogen and 25.91-27.31% for Type Ⅲ kerogen. At the peak of oil generation, the compensation coefficients of the light hydrocarbons are as follows. 27.39-72.18% for Type I kerogen, 20.74-69.80% for Type Ⅱ kerogen and 36.60-86.96% for Type Ⅲ kerogen. Studies are carried out on the regularity of C₁-C₁₄ hydrocarbons generation during various heating stages for different types of kerogens, as well as on the retention effect of various rocks and minerals on hydrocarbons.