This invention discloses an injection molding machine and a heat-insulating structure of a barrel thereof. The heat-insulating structure covers the barrel of the injection molding machine. The heat-insulating structure includes a plurality of heat-insulating units and a plurality of heat-resistant interlinings. The heat-insulating units are disposed on an outer surface of the barrel in turn along an axial direction of the barrel. The heat-resistant interlinings are located between the heat-insulating units and connect the heat-insulating units, respectively. Each heat-insulating unit includes a heat-resistant layer, a heat-insulating material layer, and an insulating layer in turn. The heat-resistant layer covers the outer surface of the barrel of the injection molding machine.