Abstract: In order to fully understand the characteristics of main source rocks and the distribution of effective source kitchen in Enping 17 Sub-sag, systematically analyze the geological background of the depression, the development environment of hydrocarbon source rocks and the geochemical characteristics, analyze the hydrocarbon generation characteristics of hydrocarbon source rocks by means of thermal pressure simulation experiments, establish the TOC probability neural network prediction model of hydrocarbon source rocks, and predict the distribution of effective source kitchen in combination with the thermal evolution simulation of hydrocarbon source rocks and the identification of the TOC lower limit of effective hydrocarbon source rocks.The results indicate that the Enping 17 Sub-sag mainly develops two sets of hydrocarbon source rocks, the semi deep-deep lake and shallow lake facies of the Wenchang Formation. The oil and gas production rates of the semi deep-deep lake facies are relatively high, with the characteristics of concentrated oil generation and late explosive gas generation; Shallow lacustrine mudstone has a relatively high gas production rate and is characterized by wide window continuous gas generation and a high lower limit of gas generation. The effective source kitchen of Wenchang Formation in Enping 17 Sub-sag are distributed in the areas where the TOC of source rocks is greater than 1.2%, mainly distributed in the sub-sag center and the northern near sub-sag on the plane, mainly distributed in the 4^th member of Wenchang Formation vertically, followed by the 3^th and 5^th member of Wenchang Formation. The facies are dominated by semi deep-deep lake facies, while the shallow lake facies source rocks are another set of important source rocks in this area. Under the high thermal evolution, oil and gas are generated simultaneously in the sub-sag, which has the development of large-scale natural gas potential, provides a resource basis for searching for natural gas in oil rich sag of the Pearl River Mouth Basin.