Abstract: At present, there are disputes on whether the degree of water retention at the turn of Ordovician and Silurian has an impact on the enrichment of organic matter. Based on the division of biostratigraphic framework, the paper analyzes the sedimentological and geochemical characteristics of shale in different periods in western Hubei, and explores the relationship between the degree of water retention and the enrichment of organic matter. The findings show that the turn of Ordovician and Silurian in western Hubei can be divided into three periods from early to late:pre-glacial period (WF2-WF3 graptolite zone), glacial period (WF4 graptolite zone-Guanyinqiao section), and post-glacial period (LM1-LM5 graptolite zone), all in deep water environment. The degree of water retention has no significant impact on the preservation conditions of organic matter; it mainly controls marine productivity and further affects the enrichment of organic matter. The depositional period of the pre-glacial WF2 graptolite zone was in the stage of platform-shelf transition, and the sea level was low. Meanwhile, the surrounding paleo-land and local underwater paleo-uplift were uplifted dramatically, the degree of water retention was the strongest (strong retention), and the nutrient exchange with the open sea was the weakest, resulting in the lowest level of paleoproductivity and the lowest TOC content (2.9% on average). After entering the depositional period of the WF3 graptolite zone, the sea level continued to rise to a high level, and the degree of water retention was weakened significantly (moderate retention). With the increase of paleoproductivity level, the TOC content increased (3.6% on average); although the sea level was the lowest in the glacial period, the rising ocean currents were extremely active and the degree of water retention was the weakest. Plenty of nutrients flowed into the Yangtze Sea Basin with upwelling currents, resulting in the highest level of paleoproductivity and the highest TOC content (4.6% on average); in the post-glacial period, the climate warmed up, Gondwana glacier melted rapidly, the tectonic activities remained stable, the sea level rose significantly to a high level, the degree of water retention was moderate, the paleoproductivity was high, and the TOC content was high (4.0% on average).