Wannian County, subordinate to Shangrao City of Jiangxi Province, is located in the northeast central part of Jiangxi Province, on the west of Shangrao City, east of Yiyang County and Guixi City, south of Yingtan City Yujiang District, west of Yugan County, north of Leping City, and Poyang County across the Le 'an River. The county covers an area of 1140.76 square kilometers, with jurisdiction over 6 towns, 6 townships and 2 administrative committees. By the end of 2021, the permanent population of Wannian County was 354,500.

In the seventh year of Zhengde (1512) of the Ming Dynasty, a county was set up in Po-Poan, Yu, Le and Guiban. The county was named after it was governed at the peak Yang of ten thousand years. The total population in the area was mainly Jiang-yo of Han nationality. Landform types in the territory are mainly hilly, supplemented by Binhu plain, the terrain from southeast to northwest inclined, in the shape of a ladder.