The boat capsized at 1:30 p.m. on Monday and all the 22 people on board fell off the boat in Yibin City, said a provincial work safety official.
As of Tuesday, 15 people had been saved while one had died and six were missing, the official said.
The provincial government has launched a search for the missing.
All the people on board were from a Sichuan Kaiji Road and Bridge Company construction project team in Gaoxian County, Yubin. They took the boat to the other side of the river for lunch. They had bought the boat from a fisherman.
The ship lost control after the rudder broke, the official said, and capsized after it hit an iron bridge pile as the team returned after lunch. The investigation continues.