To alleviate the degradation of the mechanical properties of cement-soil brought about by freeze-thaw cycles, a solution involving the addition of liquid paraffin has thus been proposed by utilizing the energy conversion characteristics of phase change materials. Firstly, based on the results of unconfined compressive strength tests, it is found that the compressive strength of cement soil reaches the highest point with a mass fraction of 3% liquid paraffin added, which is about 7% higher than that of plain cement-soil. Subsequently, freeze-thaw cycling tests reveal that under the same number of cycles, the appearance of liquid paraffin cement soil deteriorates slower than that of plain cement soil, with a less loss of quality and strength, yet a relatively higher unconfined compressive strength. Finally, a comparison and analysis are made of the micro-structure of cement soil and liquid paraffin through scanning electron microscopy experiments, revealing the damage mechanism of water soil under freeze-thaw cycles as well as the improvement mechanism of liquid paraffin on cement soil. The research results show that the addition of liquid paraffin helps to significantly improve the freeze-thaw degradation of cement soil, with the strength loss of liquid paraffin cement soil 8.56% less than that of plain cement soil after freeze-thaw cycles, which verifies the remarkable improvement effect of the liquid paraffin.