Based on the actual environment of embankment projects along the Heilongjiang mainstream, the distribution of temperature field, water field, and stress field of typical sandy soil samples from the embankment under freeze-thaw cycle were tested by the water migration experimental device. The test results showed that the damage of concrete highway at the top of embankment is related to the uneven settlement of embankment. The temperature change causes the gradient change of moisture content in embankment foundation, resulting in the change of stress field, and there is a linear relationship between the temperature gradient and moisture content gradient. The stable freezing depth of foundation reaches 1.12 m. Combined with the measured data, a thermo-hydro-mechanical coupled model for embankment foundation in seasonal frozen soil area was established. Finally, the practicability of the model in embankment projects was proved by a simulation analysis with the ANSYS finite element software.