Abstract: To investigate the abrasivity of frozen soft rock in the Cretaceous-Jurassic strata and its temperature-dependent mechanism, soft rock from the No. 2 return air shaft of the Subuerga Mine in Inner Mongolia was selected as the research object. Based on an improved low-temperature Cerchar Abrasive Index (CAI) test system, abrasivity tests were conducted on siltstone, fine sandstone, and mudstone under different subzero temperatures (−5 °C, −10 °C, −15 °C, −20 °C, −25 °C). Meanwhile, an optical microscope and a laser confocal microscope were utilized to scan the morphology of the worn steel needle tip and the three-dimensional morphology of the scratch grooves on the rock surface. The abrasive characteristics of frozen soft rocks were systematically analyzed. The results show that CAI exhibits a negative linear correlation with temperature but a positive linear correlation with uniaxial compressive strength. The variation rate of rock abrasivity is jointly governed by the coupled effects of mineral composition, internal structure, and mechanical behavior. Significant differences in needle wear morphology were observed among different rock types, with wear mechanisms categorized as coarse-particle wear, fine-particle wear, and inclined wear. Essentially, the rock abrasivity test represents a process of extrusion and shear failure of rock induced by the steel needle.