The landslide followed several days of rain and came about a month after earthquakes that killed at least 80 people in the region.
All 18 elementary school students buried in a landslide were confirmed dead Friday, while one other person also died after a hillside collapsed and smothered part of a village in mountainous southwestern China.
China's Official Xinhua News Agency said that it had rained continuously in the region since September 1st and that when the landslide occurred, the accumulated precipitation was more than 297 mm, three times the normal level from previous years.
The hillside used for farming was steeply sloped and had loose soil saturated with rainwater, which triggered the mudslide, said Xinhua.
The Tiantou Elementary School was buried Thursday when the hillside collapsed in Zhenhe, a village in Yunnan province, the Yiliang County government said on its website.
The landslide blocked a river, causing its water to pool 15 metres across and 7 metres deep around the buried area, hampering rescue efforts and forcing the evacuation of 800 other people, the government said. Rescue teams removed the blockage and the water was subsiding.
A series of quakes last month left 81 people dead and devastated parts of Yiliang county, which are still recovering.
Chinese Premier Wen Jiabao visited Yiliang shortly after the quakes in September and made a second trip there on Friday, when he visited some of the victims families and offered his condolences.
Local authorities have released names of the 18 students, and state media have distributed the full list.
Thursday was a holiday across China, but the students who were killed had been attending school to make up for days missed after the quake, Yiliang officials said. Xinhua said their school was damaged in the quake and they were sent to Tiantou temporarily.
With Files from The Associated Press