The essence of water infiltration in loess area is the joint action of water and air migration. Under the influence of heavy precipitation of a long period, moisture infiltration is easier to form a closed condition at the bottom of the soil layer away from the slope, and an open condition is formed near the slope area. In order to analyze the water-air migration law in loess, the remolded soil column test was carried out under closed and open conditions, and the measured data of water content and air pressure in soil columns were statistically analyzed. The results showed that under the open and closed conditions, migration velocity of the wetting front was the largest at the beginning, the volume moisture content increased first and then decreased. The moisture content decreased and then tended to stabilize under the closed condition, whereas the moisture content still fluctuated slightly under the open condition. Besides, under the open condition, the air pressure difference increased first and then decreased, and eventually oscillated near 0. While under the closed condition, the air pressure difference of the shallow layer rose with fluctuations, and that of the deep layer oscillated and then decreased to a stable rate. Therefore, in the process of landslide treatment, the influence of water and air should be considered at the same time to formulate more comprehensive and efficient prevention and control measures.