Zhaoyuan County (Chinese: 肇源县; pinyin: Zhàoyuán Xiàn), formerly Rear Gorlos Banner, is a county in the west-central part of Heilongjiang Province, China, bordering Jilin province to the south.

The southernmost county-level division of Daqing City, it has a land area of 4,198 km2 (1,621 sq mi) and a population of 450,000.

The county seat is located in Zhaoyuan Town.

Some farms in Zhaoyuan county with alkaline soil are experimenting rice cultivation with hybrid saltwater-tolerant rice.

2 Formally part of Oroqen Banner in Inner Mongolia but administered de facto by Daxing'anling Prefecture in Heilongjiang.