Abstract: The geological background of the Huangshui River Basin is complex and diverse, and there are significant differences in the disaster mechanism and stability of different types of landslides. In order to reveal the deformation characteristics and stability of loess slopes under different rainfall conditions, this paper takes the unstable slope of Lijiama as an example. The ' sky-air-ground ' observation technology is used to carry out on-site observation and investigation of the slope. The double strength reduction method is adopted to simulate the slope displacement, stress-strain and safety factor under natural and rainstorm working conditions. The stability of the slope under different working conditions is analyzed and verified. The results show that the unstable slope of Lijiamo is nearly semi-circular, which will be transformed into a landslide disaster under the combined action of artificial slope cutting and heavy rainfall. The toe of the slope first destabilizes and slides, resulting in the loss of support in the middle and upper parts and sliding, which is a ' traction ' landslide. At present, the slope is in a stable state. Affected by the development of a large number of tensile cracks on the slope, local sliding may occur, but heavy rainfall is more likely to cause slope instability. From June 2019 to September 2023, the average annual vertical deformation rate of the slope is-4.50 ~ 1.96 mm / a, and the average annual north-south deformation rate is-0.41 ~ 0.44 mm / a; from October 2023 to April 2024, the maximum settlement of the vertical slope of the slope is - 9.77 mm, and the maximum uplift is 9.77 mm. The maximum settlement of the north-south slope is - 161.31 mm, and the maximum uplift is 54.94 mm, which is in a stable state. Under natural conditions, the safety factor of the slope is 1.21; under the condition of rainstorm, the safety factor of the slope decreases from 1.21 to 0.93, which is an unstable state. The horizontal displacement is the largest in the middle of the slope, which is 12.94 cm, and the vertical displacement is the largest at the top of the slope, which is 12.24 cm. From the above results, it can be seen that the combination of ' sky-space-ground ' observation technology and dual-intensity reduction method can provide more comprehensive multi-source heterogeneous data support for slope research and improve the accuracy of slope stability analysis under different working conditions.