The high-temperature swelling and subfreezing frost heave of the tunnel surrounding soil are indispensable parts in analyzing the tunnel stability in swelling soil. In this paper, the physico-mechanical properties of paleosol and loess in the Loess Plateau were compared, and the temperature distribution of the surrounding soil and interior wall of the tunnel in the swelling paleosol layer was measured. The temporal and spatial distributions of high and low temperatures in surrounding soil during construction were compared using the numerical model, and the sensitivity of surrounding soil temperature was discussed. The results show that the Q(1) paleosol has the largest dry density, liquid-plastic limit, clay content, clay mineral content, and mechanical strength compared with the loess from the Q(3) to Q(1) strata. The swelling pressure of the Q(1) paleosol gradually decreases with increasing water content, but increases with increasing temperature. During the tunnel excavation in the thick paleosol layer, with the decrease in water content, the surrounding soil temperature and the duration of high-temperature swelling increase under the influence of high-temperature shotcrete, but the surrounding soil temperature and the time to enter subfreezing frost heave decrease under the influence of subzero-temperature air. In analyzing the time required for the surrounding soil temperature to vary to a specific value, the influence of water content should be given priority if the values are 80, 0, and - 10 degrees C, and the influence of air temperature should be given priority if the values are 60 and 70 degrees C.