Abstract: A existing building is located on the slope crest. To increase the usable floor areas, the top edge of the slope needed to move outside for 10meters. The refore a retaining wall was demanded to reinforce the slope. According to the project's topographical, geological and surrounding environment conditions, variable cross-section pile-plank Retaining Wall was adopted. To control the displacement of the pile-top, cemented soil was used as backfill soil. The monitor results show that the deformation of the piles and the existing building on slope crest is quite small. The above monitor results prove that the supporting system is safe and reliable.