Abstract: Vacuum combined surcharge preloading method is a commonly used foundation treatment method in coastal areas of China. However, there is a lack of engineering cases and construction experience in dam construction projects in the northern regions. Specifically, the adaptability of the conventional PVD installation process and sealing wall process to complex stratum is not clear, the sealing effect of the sealing membrane after large volume dam loading is unknown, and in winter the freezing force may damage the saturated sealing and drainage system. For this purpose, based on an earth dam project in northern China, a pilot test section was selected and installation test of prefabricated vertical drains, formation test of the sealing wall, protection test of sealing membrane and anti-freezing test of the dam foundation were carried out. The test results show that the crawler type vibratory installation process can effectively penetrate the overlying hard soil layer, and its construction efficiency is better than “pilot hole + vibratory installation process”. The 1.2 m double-row mud mixing wall can play a good sealing effect. Non-woven cloth and woven cloth are laid on the surface of the sealing membrane, and the lightly compacted transition layer can effectively protect the sealing membrane. A 2 m anti-freezing layer on the upper layer and the foot of the earth dam can effectively protect the foundation soil layer and drainage system from freezing, and the drainage system can operate normally after the winter period.