Abstract: Systematical experiments were mode on Chloroform extraction of source rock. Based on the result of the experiments, certain modifications and complements to the "Operating Manual of Chloroform extraction of source rock" are suggested. 1.The extractions are almost completed in a duration of 72 hours for detritus and 48 hours for carbonates. 2.The temperature for removing residual solvent in the extracts Should be lowered to 55-60℃(instead of 60-65℃)in order to keep lighter components in the extracts. 3.To seperate the element sulfur dissolved in solvent from organic extracts can be carried out during extraction by placing thin plates of red copper in the bottom of soxhle extractor,the element sulfur is reduced into cupric sulfide and pricipitated. 4.The commercial chloroform should be purified and the filter paper should be pre-extracted in order to minimize the blank to less than I mg fer each run.