Taking the second一term engineering of Jing一Hua freeway as research object, laws of sub-grade settlement under dynamic loading through analyzing the engineering properties of subgrade-fill-ing was studied taking tests on the spot and laboratory experiments and simulating with the finite el-ement software ANSYS. The test results show that the subgrade settlement is affected by both the speed and load cycles; the subgrade settlement decrease with the depth of subgrade increasing;extremal point of subgrade settlement is below the cyclic loading and the maximum settlement is about 9.624 cm.