Authorities barred 30,000 people living in Yumen in the northwestern province of Gansu from leaving, while road blocks prevented others from entering, after a 38-year-old died from plague last week.
"We have not discovered any new plague cases," the state-run China News service cited Gansu's health bureau as saying.
It added that authorities had exterminated rodents and fleas in designated quarantine zones, while 151 close contacts of the man had been kept in isolation for nine days without showing symptoms.
Reports said that earlier this month the victim had fed his dog with a dead marmot, a small furry animal similar to a squirrel, and developed a fever the same day.
Bubonic plague is a bacterial infection best known for the "Black Death", a virulent epidemic of the disease that killed tens of millions of people in 14th century Europe.
A more recent pandemic, the Modern Plague, began in China in the 1860s and reached Hong Kong by 1894, the US Centers for Disease Control (CDC) says on its website.
If diagnosed early, bubonic plague can be successfully treated with antibiotics, according to the World Health Organization, but in its pneumonic form it can be passed from person to person and is "one of the most deadly infectious diseases".
Cases occasionally emerge in China. A villager who found a dead marmot and ate it with other residents of Litang in Sichuan province, in the southwest, died of plague in September 2012, a newspaper run by the health ministry reported.