Loess cave dwellings is a residential building with local characteristics in northwest China. In order to explore the influence of loess rainfall infiltration on the water migration law and stability of cave dwellings, the loess of an abandoned cave dwelling in the suburbs of Yan’an was selected as the research object, and indoor experiments were carried out to obtain the soil-water characteristics and unsaturated shear strength of loess. The COMSOL finite element software was used to establish the cave dwelling model, analyze the water migration law and stability changes of the cave dwelling under rainfall conditions, and explore the effects of factors such as rainfall duration, rainfall intensity and rainfall type on the moisture field and stability of cave dwelling. The results show that: Rainfall infiltration leads to a sharp increase in the water content of the soil covering the cave dwelling, moisture continues to accumulate around and the arch of cave dwelling which result in a continuous decrease in the safety factor of the cave dwelling. The greater the duration and intensity of rainfall, the greater the decrease of safety factor. Compared with long-term weak rainfall, short-term heavy rainfall had a greater impact on the moisture distribution of deep soil in cave dwelling, and the stability of cave dwelling decreased sharply in a short time. The change of safety factor of the cave dwelling lags behind the rainfall process. The vertical displacement generated by the forward type rainfall is the largest, and the decrease in the safety factor of the cave dwelling is also the largest. But the safety factor of the peak rainfall after the rainfall is the smallest, which is the most unfavorable to the stability of the cave dwelling.