What is the most spoken dialect in China?

The most widely spoken dialect in China is Mandarin, which is said to have nearly 1 billion speakers. Mandarin is the first-level dialect of Chinese with the largest population and widest distribution as native speakers. Its name comes from the ancient Chinese name for the official standard language of Chinese.

Mandarin can generally be subdivided into eight sub-dialects: Northeast Mandarin, Jiaoliao Mandarin, Beijing Mandarin, Hebei-Lu Mandarin, Zhongyuan Mandarin, Jianghuai Mandarin, Lanyin Mandarin, and Southwest Mandarin. Among them, Southwest Mandarin has the largest number of native speakers, with more than 270 million.

Southwestern Mandarin is mainly distributed in most Chinese-speaking areas in and around Sichuan, Yunnan, Guizhou, and Chongqing in the southwest. The largest subdivisions, Sichuan-Guizhou and Xishu, have a population of more than 150 million. It is commonly known as Guizhou dialect and Sichuan dialect.

So the dialect with the largest number of speakers is Mandarin, and further speaking, it is Southwest Mandarin. Hope this helps.