Abstract: Based on more than 30 surface stations situated at a height near 3000 m and more 10 resonde stations the pressure systems over the mountaneous region of Western Kansu are analyzed. Five meso-pressure systems, two highs and three lows are found on the mean chart. The annual variations of their intensity and positions are discussed. Two case-studies are made of these meso-systems. Finally the relationship between the temperature field and these meso-systems is discussed.