Blowdown or Blowing down may refer to:

• Windthrow or forest blowdown, a felling of trees by windstorm
• Blowdown stack, a vertical containment structure at a refinery or chemical plant
• Blowdown, a process plant controlled or emergency depressurization
• Boiler blowdown, a steam-boiler process to remove impurities
• Blowdown, a television series focusing on explosive demolition
• in mathematics, the inverse of blowing up
• "Blowing Down", song from the Digable Planets studio album Blowout Comb