The South Australian government should provide free school lunches to reduce child poverty, encourage healthy eating and ease cost of living pressures, the Greens say.

Greens MP Robert Simms says with thousands of South Australian families living in poverty and the cost of living continuing to soar, government should be doing everything possible to provide relief.

"Free school lunches would reduce pressure on parents, improve educational outcomes and ensure every South Australian child has access to healthy, nutritious food," Mr Simms said on Monday.

"This measure would really help tackle growing poverty across our state.

"With so many families doing it tough, now really is the time for the government to back a bold plan like this."

Mr Simms said a report released by SA Council of Social Service in 2018 found more than 22,000 South Australian children were living in poverty.

A 2021 study by Flinders University also found the delivery of school-provided lunches could be a solution to better childhood nutrition and learning.

The study found it would involve all children in a school being provided with the same nutritious diet, with less room for sweet, salty or fatty treats.

"A universal school-provided lunch model could help ensure all children have access to food at school, reduce the stigma of children not having lunch or having different types of foods to their peers, and help ensure children are provided with healthy lunch options," nutrition and dietetics researcher Rebecca Golley said.