The qualities and the causes of the tropical easterly jet stream over Asia and Africa are described,the relationships among the Tibetan High and the easterly jet stream in the upper trope sphere and the climates in the region of the Asia and Africa are also discussed.Temperature shears occur frequently in the vicinity of the tropical easterly jet stream over Asia,therefore the vicinity of the tropical tropopause 16-17km has now become a region of interest to high--level aviation. We must pay more attention to study the information regarding the tropical easterly jet stream at this altitude over nearly half of the tropics for about half of a year.