Abstract: The settlement of subgrade during highway filling period and after construction directly affects the quality of highway construction and the maintenance costs during the run time. The settlement of loess roadbed at different filling stages is analyzed by using Settle3 D software to simulate natural and rainfall conditions,so as to obtain the deformation rule of loess highway subgrade during filling period. The results show that the settlement is in the shape of the " bathtub" as a whole. The settlement in the center of the subgrade is the largest,and the settlement decreases gradually along the centerline. The settlement decreases with the increase of depth,and the settlement on the bearing layer surface is the largest. The settlement difference between different construction stages has a nonlinear decreasing trend. At the last stage of construction,the settlement deformation of loess tends to be stable. The settlement of undisturbed loess is higher than that of compacted loess at the same stage. Rainfall increases the settlement of undisturbed loess subgrade,but the effect on the settlement of compacted loess is not apparent. Therefore,it is vital to control the compaction quality of the subgrade and to take the waterproof and drainage measures.