Big Stone County is a county located in the U.S. state of Minnesota. As of 2000, the population is 5,820. Its county seat is Ortonville.

According to the U.S. Census Bureau, the county has a total area of 528 square miles (1,367 km�), of which 497 square miles (1,287 km�) is land and 31 square miles (80 km�) (5.86%) is water.

Official Big Stone County website