Government forecasters warned of more "torrential rains" in the densely populated south, especially around the Pearl River Delta northwest of Hong Kong - the heart of China's booming export industries.
Damage was worst in southern China, where rains and mudslides have killed at least 97 people this week and left another 41 missing, the official Xinhua News Agency reported.
The death toll was higher than most of the rainy seasons of the past decade, though still below that of 1998, when 4,150 people were killed in summer flooding in central and northeastern China, Xinhua said.
Nationwide, a total of 137 people were missing, while economic losses were estimated at 20.4 billion yuan (US$2.5 billion), the report said. About 1.5 million people have been evacuated from a six-province swath.
Especially hard-hit was Guangdong province, which borders Hong Kong. It is China's most populous region, with more than 100 million people and thousands of factories that feed export industries, news reports said.
Roads and railways in Guangdong were cut by rising floodwaters, including the main Beijing-Hong Kong rail line, Xinhua said.
So far, most damage in Guangdong appears to be to farms, with export-oriented factories largely unaffected, said Ruby Zhu, China economist for the Hong Kong General Chamber of Commerce.
"But if it gets more serious, we're not sure what will happen in Guangdong province," she said.
A front-page photo in the Guangzhou Daily newspaper, published in Guangdong's provincial capital, showed floodwaters so high in one town they nearly reached the top of telephone poles.