More than 4,000 people, including armed police and forest workers, launched a "general attack" at 6:00 pm on Saturday on the blaze in an area of virgin forest in the Oroqen Autonomous Banner of Inner Mongolia Autonomous Region, bordering Heilongjiang Province, said a spokesman with the fire-fighting headquarters.
"The fire had been basically brought under control 12 hours later by 6:00 am on Sunday," the spokesman said.
Another 1,000 people had arrived at the scene Sunday morning to reinforce the fire fighting team, he said.
"Currently, the site of fire is blanketed in heavy smoke accompanied by small, sporadic blazes, and more than 5,000 people are clearing the area to extinguish all fires completely," he said.
Eighteen helicopters had also been used to put out the fire during the past several days.
Initial investigations show that the fire was triggered by lightening strikes and it had spread to 16 square km in the country's largest forest zone.