Matthew Scown was seen smiling and laughing after he was given a suspended sentence over the death of Tyrell Cobb, the four-year-old son of his then girlfriend.

There is anger over an Australian man who admitted the manslaughter of his step-son laughed and smiled as he walked free after being given a suspended sentence.

Matthew Scown was sentenced on Wednesday to a maximum four years' jail for the manslaughter of four-year-old Tyrell Cobb, having already spent two years and eight months in custody

He had initially been charged with murder but pleaded guilty to lesser charge ahead of sentencing.

Tyrell Cobb's mum Heidi Strbak also faces charges over his death in 2009.

Justice Martin Burns said Scown was not responsible for the injuries that killed Tyrell, but had failed in his duty of care to the boy who died on the Gold Coast in May 2009.

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The boy had 53 bruises and 17 abrasions from head to legs when he died, the court heard. In 2009, a pathologist believed Tyrell suffered severe internal injuries in the days leading up to his death.

Scown was accused of failing to get him any help and his mother Heidi Strbak was also charged with his murder and torture.

Queensland Premier Annastacia Palaszczuk said she would ask the state's Attorney-General to look at the sentence, which has angered child protection advocates who think it was unacceptable and were appalled by Scown's response.

"I'm angry too. How insensitive is that for the man to be laughing after the death of his stepson. Absolutely, absolutely unacceptable," Palaszczuk told Nine on Thursday.

Scown walked out of the Supreme Court in Brisbane smiling and laughing, but founder of child protection agency Bravehearts Hetty Johnson wasn't.

"They're doing all these plea bargains just to move cases through ... (it's) expedition at the cost of these kids," she told the Courier Mail.

"I think if the DPP had the resources and the backbone they should have gone for him (Scown)."

Palaszczuk said she couldn't judge the sentencing decision, but was willing to listen to suggestions for changes.

"If (Ms Johnson) has any ideas of how to improve the system I'm all for it."