The breakthrough of marine shale gas exploration in complex structural areas is hindered by the variability of preservation conditions under different burial scenarios, and the underlying mechanism driving these differences is still unclear. This study investigates the dynamic evolution of Silurian shale burial, hydrocarbon generation, and uplift, considering temperature and pressure fields. We quantitatively restore shale gas occurrence form and content, combined this with statistical analysis of key geological parameters and experimental big data of gas content. Based on these analyses, we divide marine shale gas burial types in southern China into 6 types: The maximum burial period of the burial- hydrocarbon generation stage and uplift- transformation stage, overpressure and normal pressure in deep and middle- shallow layers. We individually examine the preservation conditions of each type, elucidating the preservation mechanisms and distinctions, ultimately establishing a comprehensive quantitative evaluation index system for shale gas preservation conditions. The results show that: 1. In the burial- hydrocarbon generation stage, shale gas is in the stage of generation and accumulation, primarily dominated by high- temperature pyrolysis gas. Shale gas formed in the maximum buried area (stage) is mainly accumulated and preserved in situ in supercritical and free states, showing overpressure- rich gas. This is attributed to low hydrocarbon expulsion efficiency and high hydrocarbon retention controlled by top and bottom sealing and hydrocarbon adsorption. In addition, the occurrence of high hydrocarbon expulsion efficiency is more likely in congenital conditions such as open faults, unconformities, and adjacent formations with high porosity and permeability, resulting in insufficient original resource potential of shale gas. 2. For deep shale gas in the uplift- renovation stage, despite some shale gas loss through lateral diffusion along bedding fractures driven by concentration differences, overpressure- rich gas characteristics persist, similar to those observed during maximum burial periods. However, when the target layer is intersected by an open fault, shale gas escapes seriously and forms abnormally low pressure. 3. The medium and shallow shale gas in the uplift- transformation stage is primarily composed of free gas, followed by adsorbed gas under overpressure, and still exhibits the characteristics of overpressure- rich gas. The preservation conditions are mainly governed by the strength of tectonic deformation, with rock mechanical behavior playing a crucial role. Shale gas dissipation occurs through lateral molecular diffusion along bedding fractures in fault and outcrop areas driven by concentration differences. Under normal pressure, the structure transformation isstrong, the shale gas is mainly adsorbed gas, and the gas content changes greatly. The primary factors contributing to the preservation of shale gas are self- sealing and hydrodynamic processes, with the adsorption and capillary pressure sealing mechanisms playing a crucial role. Shale gas loss occurs due to molecular diffusion along microfracture systems driven by concentration gradients, as well as seepage and escape through open 〖JP〗faults and outcrop areas under pressure differentials and hydrodynamic forces.