The permeability of loess is crucial for engineering and disaster prevention in loess regions. Factors influencing the saturated permeability of compacted loess were analyzed. Saturated seepage experiments, scanning electron microscope (SEM), and image processing techniques were employed to assess the impacts of seepage time, dry density, temperature, and pore structure. The results indicate that silty loess has larger pores and pore throats and better connectivity than clayey loess. The average pore fractal dimension of clayey loess (1.71) is higher than that of silty loess (1.65), indicating more irregular pore shapes in clayey loess (P < 0.01). In short-term seepage, the hydraulic conductivity decreases by 3.03% for clayey loess and 19.93% for silty loess. In long-term seepage, the hydraulic conductivity increases by 57.10% and 64.39%, respectively, due to the leaching effect. The average saturated hydraulic conductivity shows an exponential relationship with dry density. As dry density increases, the hydraulic conductivity decreases by 97.30% and 94.89% for clayey and silty loess. Temperature rises led to hydraulic conductivity increases of 39.32% and 30.01% over time for both loess, mainly due to reduced fluid viscosity. Further analysis reveals that pore structure is the key factor controlling permeability changes, and other factors' impacts on permeability are closely related to pore structure changes. This study provides significant scientific evidence and technical support for infrastructure construction and geological disaster prevention in loess regions.