The invention provides a conical tri-rotor continuous mixing unit with rotors in linear arrangement, mainly comprising a mixing part and an exhausting part and a single-order or dual-order mode is adopted in the unit. The mixing part mainly comprises a charging device, a cylinder, conical rotors, a heating and cooling device and a driving device; the central lines of the three conical rotors for mixing are in the same plane and form fixed cone angles in linear arrangement in installation; the outer diameter outlines of the three rotors are tapered and each motor is provided with a charging segment and a mixing segment; the charging segment is of a spiral conveyance structure; and for a conical surface vertical to the outer outlines of the rotors, the mixing segment is of a cam shape, S shape or quadrangular rotor shape and the like. When the single-order mode is adopted, a spiral structure is adopted at the tail ends of the rotors so as to form a pressure to transmit materials to a machine head; and when the dual-order mode is adopted, mixing materials enter into the next-order screw extruder by a valve to form a pressure to transmit the materials to the machine head. For the two modes, the machine head suitable for a cavity is utilized to carry out pelleting or molding, and for the purpose of intensifying the pressure, a melt pump can be connected with the machine head. The three rotors can rotate at the same speed or different speeds, and when the three motors rotate, multiple shearing areas, stretching areas and kneading areas are formed, thus the materials among the rotors are exchanged frequently, thereby improving the plasticating performance, the melting performance and the dispersion performance effectively, shortening the processing time and improving the yield. The mixing unit is used for mixing, pelleting and other processes in processing rubbers, coatings, propellants, explosives, paper pulps, plastics, foods, pharmacy, feeds and the like.