The party has suggested seven potential sites for the new parks, in Wester Ross, Galloway, Glen Affric, Harris, the Borders, Ben Nevis and on the west coast.
Decisions would be reached about the new parks based on local support, the contribution to public access and the potential for the protection of wildlife.
The current national parks, Loch Lomond and the Trossachs and the Cairngorms, would also see their funding double under the plans, as well as the creation of regional parks.
Speaking ahead of a visit to Loch Lomond on Tuesday, Greens co-leader Patrick Harvie said: “A Scot invented the notion of a national park, so it’s shameful that we have so few here in Scotland, and those that we do have are in poor condition and under threat.
“Unlike the great American national parks, ours are not run for and by the people, but instead are dominated by grouse shooting and commercial developments that threaten vital wildlife habitats.
“The Scottish Greens will renew our national and regional parks as part of our bold, co-ordinated efforts to restore nature and tackle the climate and nature emergencies.
“That means at least doubling the number of national parks and creating regional parks to restore our natural environment, boost tourism and create rural jobs.”
The party’s plans would also see the creation of a National Parks Service to support the management of parks across the country, while park authorities would be given more powers to grant subsidies within their boundaries to support land restoration.