In an interview, Scott Morrison said he had "not made any final decisions" on attending, suggesting it was a burden.
"It's another trip overseas... and I've spent a lot of time in quarantine," he told the West Australian newspaper.
The COP26 summit will be the biggest global climate crisis talks in years.
It is hoped that the 12-day meeting between world leaders in Glasgow, Scotland will produce the next emissions standards to slow global warming and keep temperature rise below 1.5C.
