Ray County () is in Tehran province, Iran. Its capital is the city of Ray.
In 2009, villages were separated from the Central District in the formation of Khavaran District, which was divided into Khavaran-e Gharbi and Khavaran-e Sharqi Rural Districts.
In 2012, Qaleh Now Rural District and portions of Kahrizak Rural District were separated from Kahrizak District in the establishment of Qaleh Now District, which was divided into two rural districts, including the new Chaleh Tarkhan Rural District. In 2018, the village of Qaleh Now-e Khaleseh was converted to a city.
At the time of the 2006 National Census, the county's population was 292,016 in 71,711 households. The following census in 2011 counted 319,305 people in 85,445 households. The 2016 census measured the population of the county as 349,700 in 96,996 households.
Ray County's population history and administrative structure over three consecutive censuses are shown in the following table.
According to the information of the State Meteorological Organization of Tehran province, the long-term average annual rainfall ofÃÂ Ray County is around 168.6 mm.