Pore water pressure is an important parameter to evaluate the deformation and stability of loess deep filled ground. In order to explore the law of pore water pressure increase and dissipation in the loess deep filled ground in the valley terrain, the pore water pressure monitoring and analysis were carried out during and after the construction period of a loess deep filled project in Northern Shaanxi. The results show that when analyzing the law of the increase and dissipation of the excess pore water pressure, the change of the hydrostatic pressure caused by compression of the soil layer and the change of the groundwater level must be deducted; the increase and dissipation of pore water pressure are mainly affected by groundwater level and filling load; when the filling speed of earthwork construction is fast, the pore water pressure increases fast. On the contrary, the pore water pressure increases slowly or even dissipates; The increase in pore water pressure during construction period has an approximately linear relationship with the increase in filling load. The pore water pressure coefficient of multistage load is less than 0.2, and the soil is always in a stable state; the dissipation of pore water pressure is slow in the following stage of construction, and it takes a long time for the settlement to reach complete stability.