The changes will also allow all shops across metropolitan Adelaide to trade on Boxing Day.

"This is sensible shop trading hours reform which strikes the right balance for workers, local small businesses and shoppers," Premier Peter Malinauskas said.

Most shops cannot open until 11am on Sunday under current laws.

The new legislation would bring that forward to 9am, and also allow shops to open on Boxing Day from 9am to 5pm.

The state government will release its draft laws for three weeks of public consultation before introducing the bill to parliament next month.

Attorney-General Kyam Maher said the changes would help deliver certainty for shoppers, workers and businesses about the trading landscape in South Australia.

At the same time, the government has ruled out moving to allow widespread shopping on other public holidays.

"We believe that public holidays are an opportunity for people to have a holiday. That's not a particularly revolutionary view," Mr Malinauskas said.

"South Australia will have some of the most liberalised trading hours of anywhere in the world."

Australian Associated Press