The highest death toll was in southeastern Guangdong province, where 18 people were killed and four were missing since the rains started Thursday, the Xinhua News Agency said. More than 72,000 people were evacuated from their homes.
The populous province is the heart of China's export-driven light manufacturing industries, but there was no word of any damage to factories or shipping facilities.
Deaths and damage were reported throughout southern China and the northwest. Torrential rains, mudslides and floods have also hit Hunan, Guangxi, Guizhou, Jiangxi and Fujian provinces, where at least 48 people died, Xinhua said.
China suffers deaths and damage every summer when seasonal rains cause flash floods.
Big cities are sheltered by giant dikes but deaths are reported in farm communities that lack protection from rising rivers, and in mountain towns that are hit by flash floods.
Millions of people in central and southern China live on reclaimed, flood-prone farmland.
Flooding and typhoons killed 2,704 people last year, according to the China Meteorological Administration. That was the second-deadliest year on record after 1998, when summer flooding claimed 4,150 lives.
In Guangxi, the floods killed 13 people and destroyed hundreds of homes, Xinhua reported. The province is a poor, mountainous region to Guangdong's west.
Thousands of students who were taking national university entrance exams in Guangxi had to move to emergency centers after school buildings were flooded, the agency reported.
Rains in Guangxi destroyed 29 reservoirs and forced 59 factories to suspend production, Xinhua said, citing Chen Rundong, deputy director of the regional flood control office.