By using the data of microwave radiometer (MWR), placed at the foot of the Liupan Mountain at Longde station in the time period from April 2018 to November 2019, and the data of radiosonde at Pingliang station, the humidity sensitivity of retrieved temperature of MWR (TM) is studied. The humidity sensitivity rate (HSR) and the zero degree drift (ZDD) are proposed for the first time. Based on the distribution characteristics of HSR and ZDD at different altitude layers, the impact from the mountain terrain on layer humidity and temperature is studied. It shows that, ① under non-precipitation conditions, the wetter the air, the larger the difference between HSR and 1.0, and the greater the value of ZDD. ② The terrain has a great impact on the vertical distribution of layer humidity. The climbing air flow or uplift air flow increases the humidity level of layers below 3km significantly. The air humidity reaches the maximum at the layer of 500m above the top of the mountain under clear days and at the layer of 1.0-2.0km above the top of the mountain under the cloudy days respectively. The difference between TM and the station actual temperature reaches maximum by 2.7 ℃. ③ The terrain affects the vertical distribution of the layer humidity and then affects the layer temperature. The downward atmospheric radiation under the cloudy days heats the lower layer and makes the average temperature of the layers below 3 km rise by 2.3 ℃, and the temperature caused by humidity sensitivity reaches 0.9 ℃, up to 1.7 ℃.