默瑟縣 (肯塔基州)

{{Infobox U.S. county
| state = Kentucky
| county = Mercer County
| county_zh = 默瑟縣
| seal =
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| founded =
| named for = Hugh Mercer (1726–1777), killed at the Battle of Princeton.
| seat =
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| area_total_km2 = 656
| area_total_sq_mi = 253
| area_land_km2 = 650
| area_land_sq_mi = 251
| area_water_km2 = 6
| area_water_sq_mi = 2
| area percentage = 0.87%
| census yr = 2000
| census estimate yr =
| pop = 20,817
| population_density_km2 = 32
| population_density_sq_mi = 83
| time zone = Eastern
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| coordinates = {{coord|{}|0|N|{}|0|W|type:adm2nd|display=title,inline}}
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默瑟縣（）是美國肯塔基州中部的一個縣。面積656平方公里。根據美國2000年人口普查，共有人口20,817人。縣治哈羅茲堡 (Harrodsburg)。

成立於1785年。縣名紀念紀念在美國獨立戰爭普林斯頓戰役中戰死的休·默瑟准將 (Hugh Mercer)。本縣為一禁酒的縣。