Tonghe County is a county of Harbin City, located in the central part of Heilongjiang Province, the southern foot of the Lesser Khingan Mountains, the northern bank of the middle reaches of the Songhua River. It spans the east longitude of 128°09 '-129°25' and the north latitude of 45°53 '-46 °40'. It is 90 kilometers long from east to west, 87 kilometers wide from north to south, covering an area of 5678 square kilometers, with Yilan in the east and Mulan in the west. In the south, the Songhua River is the boundary with Yilan, Fangzheng and Bin County across the river, and in the north, the Pingdingshan Watershed is the boundary with Tieli and Qing 'an. According to the seventh census, the permanent population of Tonghe County was 179,828 as of midnight on November 1, 2020.

The terrain of Tonghe County inclines from north to south, like a "horseshoe shape". The north is mountainous and shallow mountainous area, and the middle is low hills and piedmont platform. In the south is the Songhua River flood and alluvial plain, located in the third accumulative temperate zone, a temperate continental monsoon climate, with an average annual temperature of 2.4℃ and average annual precipitation of 610 mm.
As of 2016, Tonghe County has jurisdiction over 6 towns and 2 townships. It has been rated as the national civilized County, the national key county of small town construction, China's famous green County, China's original ecological rice Township, the National village cleaning action advanced county. In 2019, the GDP of Tonghe County reached 8.61 billion yuan.