Abstract:During the autumn of 2014, mean precipitation over China was above normal, especially in West China with strong intraseasonal variations. Analysis shows that the positive precipitation anomaly over West China is possibly caused by the warming over the tropical Indian Ocean. The warming of the tropical Indian Ocean enhances the low level anticyclonic anomaly over the Northwest Pacific and southeast water vapor transportation to West China, and also intensifies the convectional activity over Indian Ocean and southwest water vapor transportation to West China. At the mid high latitude, abnormal trough maintains over the Lake Baikal, which is prone to guide the cold air down to West China. At the same time, the intensified western Pacific subtropical high (WPSH), whose high ridge extends more westward, also brings more water vapor from the low latitude to West China. As a result, the intensified water vapor and the northwestward cold air flow leads to the positive precipitation anomaly over West China during autumn of 2014. Furthermore, the intraseasonal variation of the autumn precipitation over West China is influenced by the WPSH.