Under the seasonal freeze-thawing action of sulfate saline soil subgrade engineering in Ningxia, it is easy to cause salt freezing and swelling damage, which leads to a decrease in strength. Therefore, based on the research of the compressive properties of solidified sulfate saline soil under freeze-thaw cycles, the compressive strength and reaction products of solidified sulfate saline soil at different ages are obtained based on five influencing factors: the number of freeze-thaw cycles, chlorine-sulfur ratio, fly ash content, calcium carbide slag content and silica fume content, through the 5-factor 4-levelorthogonal test design and unconfined compressive strength test and XRD diffraction test. The test results show that: 1) The effects of various factors on the unconfined compressive strength of solidified sulfate saline soil in 7～28 d are silica fume content ＞ calcium carbide slag content ＞ freeze-thaw cycle number ＞ chloride-sulfur ratio ＞ fly ash content, and the effect of silica fume content on the strength is significant. 2) The design ratio with the best freeze-thaw resistance effect for 7 d is as follows: the number of freeze-thaw cycles is 3 times, the chlorine-sulfur ratio is 0.1, the fly ash content is 15% , the calcium carbide slag content is 8% , the silica fume content is 7% , and the compressive strength is 5.20MPa . The optimal design ratio of freeze-thaw resistance in 28 d is as follows: the number of freeze-thaw cycles is 3 times, the chlorine-sulfur ratio is 0.1, the fly ash content is 25% , the calcium carbide slag content is 8% , the silica fume content is 7% , and the compressive strength is 7.32 MPa. 3) Under the synergistic effect of three solid waste materials, cementitious substances such as calcium silicate hydrate (C-S-H), calcium aluminate hydrate (C-A-H), calcite (AFt) and calcium sulfate (CaSO₄? ) are generated, which are interconnected with the soil skeleton to form a stable and solid spatial network structure, which promotes the overall improvement of soil body strength.