Abstract: Xinjiang open-pit mining area is located in an ecologically fragile area, where the spoil heap soil is subjected to intense human disturbance. The natural and human interference has exacerbated the water shortage, leading to the prominent soil salinization. Water has become the key factor limiting ecological restoration in the arid region of Northwest China. In order to investigate the influence of different application rates of soil amendments on the water retention and holding performance of highly saline-alkaline soil, the surface soil of a dump in an open-pit mining area in Xinjiang was used as the experimental objec,and one-dimensional column infiltration experiments and soil leaching experiments were designed. By adding different concentrations of γ-PGA and humic acid to the soil surface, the study analyzed the changes in soil water retention and holding performance caused by the application of γ-PGA and humic acid, and fitted the measured data to study the suitability of γ-PGA and humic acid for the spoil heap soil in the mining area. γ-PGA can improve the infiltration characteristics of highly saline-alkaline soil. Compared with the blank group, the advancing front velocity of the wetting front was significantly reduced and the cumulative infiltration volume decreased by 3.6%, 4.1%, 2.1% and 4.8% with the combined application of γ-PGA and humic acid. The fitting results of the Philip model and the Kostiakov model show that as the application rate of γ-PGA increases, the influence of γ-PGA on soil water movement parameters becomes increasingly significant. With the increase in the application rate of γ-PGA, the Philip model is more suitable for fitting the modified soil water infiltration in the group of combined application of γ-PGA and humic acid. Compared with the blank group, the soil surface salt ion content was significantly reduced in the combined application of γ-PGA and humic acid; the volume of leaching liquid was reduced by 11.85%, and the soil surface and 10 cm deep water holding capacity were increased by 165% and 133.68%, respectively, with the increase of γ-PGA application rate. The combined application of γ-PGA and humic acid in the saline alkaline soil improved the infiltration characteristics and water distribution of the soil, enhanced the soil's water retention and water holding capacity, and improved its resistance to salinization.