The Kumtagh Desert is an extremely arid desert, while the Altun Mountains, southward of the Kumtagh Desert, is quite moist. Thus, We expect that a comparison of the precipitation in these two regions could provide some insight about the water supply mechanism and topography formation of the Kumtagh Desert. To this end, we analyzed China automatic observation stations-CMORPH combined 0.1° grid hourly precipitation dataset. We first found that precipitation in the Kumtagh Desert mainly concentrated in summer while concentrated in spring and autumn in the Altun Mountains, and that there existed a large precipitation belt in the Altun Mountains, which was most extensive during March but almost disappeared in summer. Therefore, the Altun Mountains mainly provided water supplement to the Kumtagh Desert during spring and autumn and precipitation of these two regions was most different in spring while almost comparable in summer. Also we found that the monthly mean hourly precipitation in the Alutn Mountains varied significantly with season: "the early morning" type dominated in December and January of winter and in June and July of summer, which may be related with instability resulted from cloud top radiation cooling; "the afternoon-twilight" type dominated in spring and autumn, which may be related with the instability resulted from surface heating by solar radiation in afternoon; February and August are the transition periods. Our findings could provide a basis for further exploration of the water supply mechanisms and the unique "feathery dunes" landscape in the Kumtagh Desert.