Abstract: In order to study the unsaturated soil-water characteristics of soil under freezing-thawing cycles, the soil in Yuanbaoshan open-pit mine dumping site was selected as the research object. The variation of matrix suction and structure of soil under different water content after different freezing-thawing cycles was studied. The results show that during the same freezing-thawing cycles, the matrix suction increases with the decrease of water content, and the range increases gradually. The soil-water characteristic curve can be divided into sensitive stage, sub-sensitive stage and insensitive stage. With the increase of freezing-thawing cycles, the curvature of soil-water characteristic curve increases first and then tends to be stable, and the sensitivity of matrix suction to the increase of freezing-thawing cycles decreases gradually. Freezing-thawing cycles destroy the uniformity of soil particles, and the influence of initial freezing-thawing cycles is the most significant. Van-Genuchten model can better predict the soil-water characteristic curve of soil. Therefore, the influence of freezing-thawing cycles on the stability of dump slope should be emphasized in the process of mine dumping.