A total of 27 people were reported dead in Jiangsu province, west of Shanghai, and nearly 40,000 were evacuated, a disaster relief official was quoted as saying.
From June 21-July 5, Jiangsu had four times the usual amount of rainfall, the Xinhua News Agency said. Weather forecasts were for continued heavy rains.
In neighboring Anhui province, three people were killed and at least 44,400 people were displaced along the flood-prone Huai River.
More than 13 million people have been affected by the storms.
Earlier this week, the government said flooding, landslides and other weather-related disasters killed at least 349 people in China in June.
Xinhua said 99 people were still missing, while damage was estimated at 20 billion yuan (US$2.5 billion).
China suffers hundreds of rain deaths every summer. The impact of flooding has been worsened by heavy farming and deforestation. Major cities are shielded by flood dikes but small towns, especially in mountainous areas, are vulnerable to deadly flash floods.
China is expected to suffer from more typhoons than usual this year due to an unusually warm current off its Pacific coast and high temperatures over the Tibetan plateau.