Abstract: Slope instability caused by continuous rainfall is one of the common geological disasters of loess slope. In order to study the influence of continuous rainfall on the seepage field, deformation field and stability of steep loess slope, the isolation slot technology with lateral seepage isolation and longitudinal drag reduction was used to treat the rainfall boundary on both sides of slope. On this basis, the field continuous rainfall (6 days) test was carried out, along with numerical simulation analysis. The cracking failure process and characteristics were described, and the water content and pore water pressure response were analyzed. The influence was also discussed of the cracking on the stability of steep slope. The results show that the isolation boundary leads to transverse through crack almost on the top of the slope, which eliminates the boundary constraint effect of the soil outside the local rainfall range substantially. The slope cracking has great influence on the distribution of water content and pore water pressure in the later stage of rainfall, which causes the center of maximum water content and pore water pressure to move down with the crack as vertical symmetry axis gradually, and the total water infiltration depth is 1.3 times that of the rainfall period 4 days after rainfall. The safety factor is reduced by 58% due to continuous rainfall of the slope, while the safety factor increases by 9% after 4 days of rainfall. The slope cracking caused the upper part of the steep loess slope to collapse easily. The research results provide a reference for the prevention and control of rainfall disaster of slope in loess area.