The outline of present status and advances in theoretical research on geochemistry of hydro-carbons in China are reviewed in this paper. The subject covers three aspects: A) geochemistry of irregular hydrocarbon, B) reservoir geochemistry, and C) geochemistry of natural gas. The first aspect consists of three parts, a) geochemistry of terrestrial lower-mature hydrocarbons, b) geochemistry of highly-mature and over-mature hydrocarbons, and c) geochemistry of hydrocar-bon from coal. The mechanisms of lower-mature hydrocarbon formation are described as the ear-ly-stage hydrocarbon generation from the special hydrogen-rich maceral in coal measures, hydro-carbon generation from degradation of organic bacteria of terrestrial inputs, and hydrocarbon generation from biolipids of higher plant and algae. Both whether carbonate source rock gener-ates early-stage hydrocarbons or not and how much hydrocarbon it can provide are related to the type and abundance of organic matter in it. In comparison with mudstone source rock, the or-ganic matter in carbonate has a wider range of R0% for "liquid window" (up to 1. 5%) in the process of hydrocarbon formation. The liquid hydrocarbons generated from organic matters of coals and coal measures during coalification may be partially discharged from the coal measure source rock and be accumulated in reservoirs. Reservoir geochemistry has shown its very impor-tant effects in studies of secondary migration, mechanism of reservoir formation, reservoir de-scription, evaluation of oil and gas resources, etc. Since there are many differences between oil and natural gas, geochemistry of natural gas as an independent discipline has been established, and the main points of the discipline include stable isotope geochemistry, genetic mechanism of natural gas, identification of genetic types, and integrated comparison of gas sources, etc.