From January 15 to 17,2007, a dusts weather process occurred around the region of Lhasa, which caused the pollution of air and the decrease of visi bility.It brought bad influence to the Lhasa's production, transportation and r esident life. The weather and climate characteristics are analyzed to depict the local meteorological conditions which cause the dust and air pollution. The r esults indicated that the causes of the dusts were the hot air confronted cold a ir on the plateau region, temperature gradient and front increasing. The st rong wind blew in the western region of Lhasa and arose the floating dusts f rom the dry and incompact surface land. A great deal of thin sand in the weak conve rgence zone went to Lhasa along with the western highlevel air current. Meanw hile, th e Lhasa's local low altitude had the steady atmosphere layer and weak wind. This weather and orographic conditions are favorable to the invasion 〖JP2〗of float ing sand, which caused the dusts breaking out, air polluting and visibility decreasing. F inally, some ideas are put forward for the forecast of dust weather in Lhasa.