A decomposed corpse found in a body bag in a Sydney national park has been identified as missing woman Lorraine Eves, with investigators saying her death may not be suspicious.

The 56-year-old artist from Dee Why was reported missing to police in June.

A NSW Police missing persons website identifies Ms Eves as a slim, caucasian woman, about 172cm tall, with brown hair and a fair complexion.

She was last seen on June 7 in the suburb of Dee Why.

Her body was found about 5pm (AEDT) on Tuesday by a man walking his dog through the Garigal National Park at Killarney Heights, in Sydney's north.

Police said on Wednesday the woman had been dead for "a few weeks" but were still to confirm a cause of death and continue to investigate if the body had been washed by recent heavy rains to the location where it was found.