Abstract: To investigate the microscopic regulatory mechanism of salinity on crude oil desorption at the quartz interface in tight sandstone reservoirs, adsorption models of four-component crude oil (acetic acid, toluene, heptane, decane) on quartz and oil-water-rock desorption models under different salinity gradients were constructed. Molecular dynamics simulations were performed, with multi-parameter analysis including relative concentration profiles, interaction energy, and centroid distance. The mechanism of salinity-crude oil component competitive adsorption was systematically elucidated. Results show that the adsorption stability of crude oil components on quartz follows the order: acetic acid > toluene > decane > heptane; Low-salinity water drives efficient crude oil desorption through the synergistic effect of electrical double layer expansion and ion bridging-induced dissociation, while high-salinity water causes delayed and incomplete desorption due to ion barrier and polarity shielding effects; The desorption efficiency ranks as low-salinity water > medium-low salinity water > deionized water > medium-high salinity water > high-salinity water. This study reveals the molecular mechanism of salinity gradient regulating crude oil desorption, providing a theoretical basis for low-salinity waterflooding in tight sandstone reservoirs.