The present invention relates to an injection molding apparatus with a spherical rotor. The injection molding apparatus includes an injection oil cylinder, an injection base frame, a motor, a transmission mechanism, bases, radial thrust bearings, a hopper, a machine barrel, an electric heater, a moving oil cylinder, a gear and a plunger. The apparatus further includes a plasticizing rotor and the plasticizing rotor includes a hemispherical rotor and a cylinder integrated with the hemispherical rotor. Continuous external thread grooves are provided on the hemispherical rotor. The machine barrel includes a hemispherical plasticizing cavity and an injection barrel. The hemispherical rotor is located in the hemispherical plasticizing cavity and is rotatable. The hopper is installed on the plasticizing cavity. The apparatus with the spherical rotor has the advantages of strong plasticizing, pulverizing and extruding ability, good quality of molded products and the like.