So far, 250 people have been injured and condition of 134 of them is said to be serious, the provincial civil affairs department said in a statement.
The National Committee of Disaster Reduction, Ministry of Civil Affairs and Yunnan's provincial government have sent 9,700 tents, 15,000 quilts, 15,000 clothes and other relief materials to the quake-hit region, state run Xinhua newsagency reported.
The earthquake toppled 1,264 houses or apartments and left 17,658 others seriously damaged, mainly in the county seat near the border with Myanmar, Zhao Yunshan, director with the county government's press office said.
More than 127,100 people have been evacuated to nearby shelters, an official with the Ministry of Civil Affairs said yesterday.
Over 80 per cent of the homes in Lameng Village, the epicentre, collapsed in the quake.
However, no serious casualties were reported in the village, Zhao said.
The epicenter, with a depth of 10 kilometers, was monitored at 24.7 degrees north latitude and 97.9 degrees east longitude, according to the China Earthquake Networks Centre (CENC).
Witnesses said people were buried under debris and part of a supermarket and a hotel caved in.
The tremor triggered a power outage but telecommunication service remained normal in Yingjiang, which has a population of 300,000 people and is home to many ethnic groups.
Altogether seven aftershocks, measuring up to 4.7 degrees on the Richter scale, has jolted the quake-prone county since the first tremor.
Experts have not ruled out the possibility that stronger quakes might hit the region later and they could not say for sure that the first magnitude-5.8 tremor was the main quake, according to Gu Yishan, an expert with the Yunnan provincial earthquake bureau.
The magnitude-5.8 tremor was the largest of more than 1,200 minor tremors over the last two months in the region, said Liu Jie, a director with the earthquake forecast department in the China Earthquake Networks Center.
According to Gu Yishan, the frequent tremors in the past months have already done some damages to buildings in the county, which might have worsened yesterday's disaster.