With the rapid development of railway networks in cold regions, frequent subgrade diseases are observed. To investigate the freeze-thaw characteristics and mechanical properties of subgrade soils in cold regions, a series of laboratory tests were conducted. The effects of moisture content, freezing temperature, and freeze-thaw cycles on soil behavior were systematically investigated. The experimental results indicate that the frost heave ratio and thaw settlement coefficient increase consistently with higher moisture content, lower freezing temperatures, and more freeze-thaw cycles. More pronounced moisture migration is observed under conditions of higher initial moisture content and higher freezing temperatures. The upper part of soil samples shows gradual moisture reduction while the lower part exhibits moisture accumulation with increasing freeze-thaw cycles. The freezing temperatures are measured as -1.96,-1.89, -2.17, -2.06 ℃ for initial moisture contents of 8%, 10%, 12%, and 14% respectively, with the lowest freezing temperature occurring at 12% moisture content. The strength variation ranges are determined as 3.63 ~ 6.15 MPa with increasing moisture content, 3.26 ~ 6.05 MPa with decreasing freezing temperatures, and 4.49 ~ 3.68 MPa with increasing freeze-thaw cycles. These findings are considered significant for ensuring the stability and safety of transportation infrastructure in cold regions.