Workers are applying waterproof materials and asphalt to the Qingshui River Bridge with a fortnight to go until traffic is permitted across.
The bridge, which cost ¥1.54billion (£158million) and took two years to build, will be 1,332ft (406m) tall and with a span of 3,707ft (1,130m).
It has been built in rocky terrain to improve transport links between the provincial capital of Guiyang and neighbouring counties.
It will shorten the distance from Weng'an county to Guiyang from about 100 miles to 23 miles, construction director Gao Heng said.
The only bridge taller than it will be the Sidu River Bridge - also in China, but in Badong, Hubei - which has a height of 1,627ft (496m).
Another major Chinese bridge under construction in Baoshan, Yunnan, will be 8,104ft (2,470m) long when it is completed next year.
It has been built in rocky terrain to improve transport links between the provincial capital of Guiyang and neighbouring counties.
It will shorten the distance from Weng'an county to Guiyang from about 100 miles to 23 miles, construction director Gao Heng said.
The only bridge taller than it will be the Sidu River Bridge - also in China, but in Badong, Hubei - which has a height of 1,627ft (496m).
Another major Chinese bridge under construction in Baoshan, Yunnan, will be 8,104ft (2,470m) long when it is completed next year.