Abstract: Macromolecule materials are added into urea-formaldehyde-resin to decrease its brittleness and contractility, and increase its water-resistance. The improved urea-formaldehyde-resin in liquid form is injected into soil. With the cross-polymer solidification happening in the soil, the soil is strengthened. It is shown that the strength andwater-resistance of the soil are largely improved through the laboratory test. The field test shows that the mud pumping of roadbed is effectively abated.