One man, Gao, whose sister was on board, told AFP: "Of course I am angry at the boat captain. How come other ships stopped, but his didn't?"
Xia Yunchen, a university lecturer whose brother was on board, interrupted a press conference by officials and called for a more detailed investigation.
"All the emphasis is on a natural disaster," she said, "but we think that this is unjust".
"Apart from natural disaster were there other causes? Is this not rational to ask?"
Ms Xia also demanded to see her brother's body, instead of receiving ashes.
Before being escorted out, she shouted at officials: "Why do you view the common people as your enemies? There's no human feeling, can't we change this habit?"
Analysis - Jill McGivering, BBC News, Regional Editor South Asia
In the past, news of a disaster on this scale might not have been reported at all in China. In the age of social media, a total blackout is almost impossible - and the main facts, including the recovery of bodies, have made headlines.
But the tone and focus of China's coverage have been very different from international news organisations. There's been no mention, for example, of protests by angry relatives of the passengers, demanding more information.
Instead, China's media carried positive stories about the courage of divers at the scene and details of their heroic rescues.
Pictures of relatives show them looking calm and composed. And there was an item too on the ship's captain - describing his struggle to keep the ship afloat and his flawless track record.
The piece, illustrated by a smiling portrait, didn't explain how he managed to survive when most of his passengers did not.