Abstract: To investigate the characteristics of water vapor sources of precipitation and their impacts on agricultural production in the Kubuqi Desert, Inner Mongolia, this study analyzed the interannual variations of precipitation hydrogen and oxygen isotopes using δD and δ¹⁸O data from the Dalate Banner station during 2001~2020. Backward trajectory model was employed to identify the water vapor sources of precipitation, and the relationship between water vapor source composition and crop yield was quantitatively analyzed. The results show that the isotopic composition of precipitation displays clear periodic variations, and the slope of the local meteoric water line (3.10) is lower than that of the global meteoric water line, indicating a dry climate with strong evaporative effects in the region. δD and δ¹⁸O were depleted with increasing precipitation but enriched with rising temperature. Moisture contributing to precipitation is mainly derived from the northwestern Atlantic moisture transported by the westerlies (65.60%), followed by Arctic moisture (19.47%), continental moisture (8.96%), and Pacific moisture (5.97%). Westerly moisture associated with the Atlantic and Arctic sources is predominantly transported in the upper atmosphere. However, due to its relatively dry characteristics, it contributes less to effective precipitation and is less favorable for crop growth. In contrast, although representing a smaller proportion, Pacific and continental moisture sources produce greater precipitation and exert a more significant positive influence on crop yield.