here are the corrections to your text:
The Yangtze River is the longest river in China.
The main stream of the Yangtze River runs across central China from west to east.
The Yangtze River originates in the southwest of Qinghai Province, from the main peak of the Tanggula Mountains on the Qinghai-Tibet Plateau.
The main stream successively flows through 11 provinces, autonomous regions, and municipalities, including Qinghai and Sichuan.
The Yangtze River drains about 1/5 of the total area of the country.
The annual seawater inflow of the Yangtze River is 951.3 billion cubic meters.
Here is the corrected text:
The Yangtze River is the longest river in China. The main stream of the Yangtze River runs across central China from west to east. The Yangtze River originates in the southwest of Qinghai Province, from the main peak of the Tanggula Mountains on the Qinghai-Tibet Plateau. The main stream successively flows through 11 provinces, autonomous regions, and municipalities, including Qinghai and Sichuan. The Yangtze River drains about 1/5 of the total area of the country. The annual seawater inflow of the Yangtze River is 951.3 billion cubic meters.