The invention discloses a preparation device for medical plasma activated water. When the device operates, aseptic pure water in a water storage tank (100) flows into an activation chamber (402) through a water pipe; a control chip (201) sends electric signals to control operating state of an electromagnetic valve (202) and a water pump (203) so as to control water supply or water drainage; after a water level indicator (403) detects that the water is full, a power supply module (300) generates high-voltage pulse current and enables a plasma generator (401) to operate and generate plasma for activating the aseptic pure water in the activation chamber (402); after the activation is completed, the plasma activated water in the activation chamber (402) flows out through a water discharging module (500). The preparation device for the medical plasma activated water can be used for preparing medical plasma activated water with various active bactericidal substances.