Chaypareh-ye Pain Rural District () is in Zanjanrud District of Zanjan County, Zanjan province, Iran. Its capital is the village of Hesar.
At the time of the 2006 National Census, the rural district's population was 4,732 in 1,043 households. There were 4,178 inhabitants in 1,065 households at the following census of 2011. The 2016 census measured the population of the rural district as 3,797 in 1,086 households. The most populous of its 13 villages was Moshampa, with 1,203 people.