In view of the problem that the compaction coefficient of cement improved silty fine sand road in Gobi area is difficult to meet the standard after the completion of rolling inspection as an engineering material, after comprehensive analysis, it is found that the timeliness of cement improved silty fine sand is not considered in on-site construction and inspection. Through the design of compaction test and unconfined compression test of cement improved silty fine sand under different delay time, the influence of delay time on the compaction characteristics and strength characteristics of cement modified silty fine sand was analyzed. Considering the strength change of Subgrade in seasonally frozen area after freeze-thaw cycle, the freeze-thaw cycle test of cement modified silty fine sand under the influence of delay time was designed. The results show that with the increase of delay time, the maximum dry density of cement modified silty fine sand first increases and then decreases, and the optimal water content first increases, then tends to be flat and then increases; The saturated 7 d unconfined compressive strength and the strength after freeze-thaw cycle decreased gradually with the increase of delay time; The structure formed by cement hydration inside admixture has been destroyed after being rolled and formed, reducing the cement effectiveness.