Abstract: Using an airflow trajectory model based on the Lagrangian method (HYSPLIT_4.9), combined with the massive gas block tracking method, the moisture transport characteristics of Meiyu in the Yangtze-Huaihe River region (YHMY) and Huaibei rainy season (HRS) are discussed and compared quantitatively in this study. The YHMY and HRS are shown to be two independent rainy seasons. The moisture in YHMY mainly comes from the Indian Ocean, the Pacific Ocean, and the Bay of Bengal-the South China Sea. Water vapor from the Indian Ocean accounts for more than 50% of the moisture in YHMY. For HRS, there is little difference between the Indian Ocean, the Pacific Ocean, the Bay of Bengal-the South China Sea, and the Eurasian continent. Compared to YHMY, the moisture from Indian Ocean decreases 20%, while the moisture from the Eurasian continent increases 19% during HRS. The water vapor from the Indian Ocean, the Pacific Ocean, and the Eurasian continent has a significant influence on the differences between YHMY and HRS in abnormal years. In wet YHMY years, the water vapor from Indian Ocean is 17% less than that in dry YHMY years, while the water vapor from Bay of Bengal-the South China Sea is 20% higher than in dry YHMY years. In wet HRS years, the moisture from the Indian Ocean is 19% higher than in dry HRS years.