Abstract: The invention discloses a thermal arc evaporation multi-cavity device for preparing nano-powder, and relates to the field of preparing nano-powder. The device is provided with at least two main chambers as powder generating units. Each main chamber powder generating unit is respectively connected to an arc power supply and a control system through a respective thermal arc control signal line and a respective feeding control signal line. The main chamber powder generating unit comprises a main chamber and a thermal arc device, wherein the top of the main chamber is provided with a thermal arc device, the bottom of the main chamber is provided with a collection chamber, the thermal arc device comprises a cathode arranged at the top of the main chamber and extending into the inner part of the main chamber, and a cathode control device for controlling the cathode to move in three directions. An anode is arranged at an opposite position under the cathode, an automatic feeding device is arranged at the back end of the anode to control anode feeding, and a cooling water device is arranged at the front end of the anode to cool the anode. This patent greatly improves the production efficiency and reduces the cost. Realize simultaneous preparation and continuous production of various powders with different components, avoid mutual pollution in powder preparation and improve powder purity.