Khak Mardan () is a village in Qarah Su Rural District of the Central District in Khoy County, West Azerbaijan province, Iran.
At the time of the 2006 National Census, the village's population was 650 in 141 households. The following census in 2011 counted 643 people in 175 households. The 2016 census measured the population of the village as 622 people in 185 households.