To clarify the effects of different grass-crop rotations on soil salinization characteristics in Ningxia"s Yellow River irrigation districts and to reveal the underlying mechanisms of soil improvement. This study investigates typical saline-alkali soils in Ningxia"s Yellow River irrigation district using field plot experiments. It examines changes in soil soluble base cations and total salt content under five cropping systems: alfalfa continuous cropping, alfalfa fallow, alfalfa-sunflower rotation, alfalfa-sorghum rotation, and alfalfa-forage corn rotation. Factor analysis was employed to comprehensively evaluate soil salinization levels under different rotation systems. Significant differences in vertical soil salinity distribution were observed across different crop rotation systems. The alfalfa continuous cropping system exhibited a surface-concentrated salinity profile, while alfalfa fallow and alfalfa-forage corn rotations showed an olive-shaped distribution. Conversely, alfalfa-sunflower and alfalfa-sorghum rotations demonstrated a bottom-concentrated salinity pattern. while alfalfa-sunflower and alfalfa-sorghum rotations exhibited a bottom-heavy pattern. Both alfalfa-sorghum and alfalfa-sunflower rotations suppressed surface salt accumulation, with total salt content in the 0–20 cm soil layer being 0.32 g·kg?1 and 0.31 g·kg?1, respectively. Factor analysis revealed that the primary saline substances in the study area"s soil were sodium-dominated chlorides or mixtures of chlorides and sulfides. The comprehensive salinization evaluation extracted two dominant factors with a cumulative contribution rate of 90.617%. The alfalfa-sunflower rotation system demonstrated relatively better overall improvement effects for saline-alkali land. This provides a reference basis for the sustainable utilization of rotation systems, saline-alkali land improvement, and sustainable utilization in arid and semi-arid regions.