The latest aftershock with a 3.7-magnitude struck the province late Saturday, killing at least one person, Xinhua News Agency reported. The victim was a 2-year-old child who was buried under a wall knocked down by the aftershock.
Multiple quakes, with some measuring up to 5.7-magnitude, have tormented the mountainous areas of the province since last Friday.
The Ministry of Civil Affairs said the number of people killed now stood at 81, and that more than 700 people had been injured. About 200,000 people have been forced to flee their homes.
Chinese Premier Wen Jiabao, who toured the disaster area and visited hospitals where the injured were taken, warned of continuing aftershocks.
"The quakes are not over yet," Wen said. "Aftershocks continue, and within a period of time we will need to guard against secondary and geological hazards."
In March of last year, a 5.8-magnitude quake, followed by hundreds of aftershocks, struck the same province, killing at least 25 people in the province's 300,000-population Yingjiang County, injuring at least 250 people, 135 of them seriously, and making thousands more homeless.
In one of the deadliest earthquakes to hit China in recent years, an 8-magnitude temblor in May 2008 devastated Sichuan, another southwest province, leaving more than 85,000 people dead or missing and injuring hundreds of thousands more.