Objectives: Tuff was developed in the Lucaogou Formation in the Jimsar Sag, Junggar Basin. And the tuff matter plays an important role in the formation of shale oil, and its development interval is also the best oil- bearing interval of shale oil. Therefore, the study of distribution of tuff matter and its relationship with the hydrocarbon generation of organic matter is of great significance for the understanding of oil and gas accumulation rules of the Jimsar shale oil. Methods: Based on evaluation source rocks and analysis its sedimentary environment, combining study of diagenetic minerals that have a genetic relationship with hydrocarbon activities, the controlling factors and hydrocarbon generation mechanism of the formation of high- quality shale oil source rocks of the Lucaogou Formation in the Jimsar Sag were discussed. Results: Qualitative analysis of source rocks indicate that muddy dolostone is main source rock of Lucaogou Formation in Jimsar Sag. The source rock has high abundance of organic matter and good hydrocarbon generation potential, type of organic matter is mainly type I and type II1. The source rock is inmature stage, with Ro value is between 0.6% and 1.1%, and C29αααS/(S+R) ratio is between 03 and 05. Distribution of regular sterane C27, C28 and C29 in source rocks of Lucaogou Formation is C27