In this paper after analyzing the diurnal variation of weather in Nan Shan region the auther pointed out the following phenomena. 1. In the high mountain region (absolute height over 4000 m) the air temperature falls down very slowly during the night time. Some times the mean diurnal variation of temperature shows semi-diurnal wave. 2. The mountain-valley winds predominant on the whole region of Nan Shan. 3. The mountain-valley winds are found to be disturbed by upper temperature trough. 4. The direction of reversed diurnally and annually.