Abstract: In order to study the influence factors of uneven settlement and long-term deformation of a loess-filling foundation, the RTK technique, borehole sampling and high-density electrical method are used to measure the in-situ ground settlement and stratum based on the treatment process of a loess-filling foundation 9 years after construction. Using the microtremor detection and borehole sampling methods, the groundwater environmental changes are investigated. The results show that: (1) The main reasons for the long-term settlement of the loess-filling foundation are the low compaction degree and the increase of water content of soils after construction. When the control compaction coefficient is greater than 0.94, the surface settlement rate can be stabilized to 0.01mm/d in 8 to 10 months after construction. (2) The settlement amount of fill increases linearly with its thickness, while the settlement amount of the original foundation increases with the thickness of overburden soil in pairs. (3) After the construction, the water content of the foundation increases to the plastic limit, and the surface settlement rate changes from 0.45mm/day to 1.70 mm/day. The long-term settlements of the fill and the original foundation linearly increase with the increment of the water content, and the unit deformation increment of the fill is 1.3 times that the original foundation. (4) After the construction, the water content of the loess-filling foundation increases to the current one. The settlement rates of the fill and in-situ foundation seven to nine years after the construction are 5.0~7.6 times and 1.0~3.0 times higher than those three to seven years after the construction. The foundation settlement is stable in 10 years after the construction.