The invention discloses an assembly and hot extrusion method for non-welded columnar insulated-porcelain multistage depressed collectors and relates to the technology of vacuum devices. Tight fit and relative positions of ceramic columns and electrodes are guaranteed during assembly by a series of high-precision assembly dies and processing measures. The assembled ceramic columns and all stages of collectors are then integrally pushed into collector cylinders on a special hot extrusion die by means of hot extrusion. As no welding measure is taken, problems of flux such as outflow and evapotranspiration are avoided. The prepared multistage depressed collectors are well voltage-resistant and structurally reliable.