The oil displacement efficiency of low-mineralization brine is mainly influenced by the interaction among crude oil, brine and rock. Clarifying the relationship among the three is crucial to understanding the dominant mechanism of enhanced oil recovery (EOR) by low-mineralization brine. High-temperature and high-pressure core flooding experiments were conducted on various crude oil samples with different emulsion formation capabilities, including spontaneous imbibition of high-mineralization brine and displacement by low-mineralization brine. The injection process of low-mineralization brine in the tertiary oil recovery mode was simulated to investigate the impact of crude oil microemulsion formation capability and rock wettability changes on the recovery rate of low-mineralization brine flooding. The results show that the cumulative recovery rates of high-mineralization brine spontaneous imbibition and water flooding for the eight oil samples range from 37.6% to 55.9%. When low-mineralization brine is continuously injected in the tertiary oil recovery mode, the recovery rate can be further increased by 0.5% to 10.8%. The stronger the microemulsion formation capability of the oil sample, the higher the recovery rate of low-mineralization brine flooding, but the upper limit of the recovery rate increase by low-mineralization brine flooding is 11%. When the crude oil particle dispersion ratio is greater than 7, the recovery rate of low-mineralization brine flooding for this oil sample can reach more than 5%. Low-salinity brine enhances oil recovery through two mechanisms. On one hand, it forms emulsions with crude oil, promoting the stripping of oil from rock surfaces and the rearrangement of active components, enhancing water-rock reactions and shifting wettability to water-wet. On the other hand, emulsification induces the Jamin effect to increase seepage resistance, raising injection pressure and displacement differential pressure under constant-rate injection, and expanding sweep efficiency. The findings provide a reference for the application of low-salinity brine flooding and the precise screening of suitable reservoirs.