The invention discloses an externally heating type vacuum heat treatment tank in the field of heat treatment equipment. The tank comprises a tank body, wherein the tank body has a closed bottom and an open top, an exhaust assembly connected with the tank body in a sealed manner is arranged at an opening in the top of the tank body, the exhaust assembly is provided with an exhaust tube communicated with the inside of the tank body, and a heat-resistant chuck arranged at a resistance furnace door opening is arranged on the periphery of the middle of the tank body. The tank has the benefits as follows: the tank is simple in structure, easy to manufacture and convenient to operate and maintain, an electrical heating element performs heating outside the vacuum tank, the vacuum discharge phenomenon cannot occur, other electrical problems such as short circuits, carbon deposition and the like are solved, besides, workpieces are sealed in the tank and cannot have chemical reactions with the electrical heating element, a furnace lining and the like, the production is safe and reliable, the vacuum tank is small in volume, few accessories are arranged in the tank, vacuum sealing is easy, the sucking quantity is small, and the required vacuum degree is reached easily.