Abstract: In 1984, a sandfly fauna survey in Aksu Region of Xinjiang revealed that the component of sandfly population was different in four landscape zones, where the soils are different. The mountainous area and ancient oasis are covered with brown calcareous soil and whitish oasis soil, where Ph. chinensis longiductus is the predominant species amounting to 91.1% and 92.5% of sandfly population respectively. In the stone desert area at the foot of the mountain covered with brown desert soil, Ph. alexandri was most prevalent, being 91.5%. While in the dry desert area covered with scrubby meadow soil where Populus diversifolia and Tamalix sp grow, Ph. major wui was' 60.9% and no Ph. chinensis longiductus or Ph. alexandri was found. According to the data of this paper and previous fauna survey made in Xinjiang, the authors suggested that the main factor influencing the geographical distribution of sandflies is the type of soil.Based on the results of the artificial infection of these 3 species of sandflies and natural infection of Ph. alexandri, it was demonstrated that all these sandflies play a role in kala azar transmission in Aksu Region. Different sandfly species play different roles in the transmission of kala azar in different areas.