A processing method for high-temperature solid steel slag, comprising: step a, coaxially and rigidly connecting a working barrel axially in series with a material feeding barrel by a flange, and arranging the axis of the material feeding barrel and the working barrel at an inclination angle with respect to the horizontal plane, wherein the material feeding barrel is set to contain adequate high-temperature solid steel slag, providing a material feeding port and its mating seal door on a side surface of the material feeding barrel, wherein the seal door can be open or closed, disposing steel balls as cooling and crushing medium and disposing a spray cooling system in the working barrel; step b, using a hydraulic bearing device to support the material feeding barrel, opening the seal door, moving a material feeding hopper to a position directly above the material feeding port, moving a slag ladle to a position directly above the material feeding hopper by traction of a traveling crane, turning over the slag ladle to pour high-viscosity slag or ladle-bottom slag in the ladle into the material feeding barrel at one time, closing the seal door and then removing the material feeding hopper and the hydraulic bearing device; and step c, rotating the working barrel and the material feeding barrel simultaneously, so that under the combined action of the gravity component force in the axial direction of the material feeding barrel and the rotating force of the material feeding barrel, the high-temperature solid steel slag within the material feeding barrel moves downwards gradually as the material feeding barrel rotates, in the form of spiral feeding, and enters into the working barrel orderly, the high-temperature solid steel slag gradually transferred from the material feeding barrel is processed in the working barrel by continuously cooling and crushing blocky high-temperature solid steel slag by the cooling and crushing medium within the working barrel, using cooling water ejected from the spray cooling system to controllably cool and immerge to the crushed steel slag so as to rapidly stabilize the steel slag and make the steel slag have a normal temperature, and to achieve a heat-exchange cooling to the steel balls, and discharging the processed solid steel slag. step a, coaxially and rigidly connecting a working barrel axially in series with a material feeding barrel by a flange, and arranging the axis of the material feeding barrel and the working barrel at an inclination angle with respect to the horizontal plane, wherein the material feeding barrel is set to contain adequate high-temperature solid steel slag, providing a material feeding port and its mating seal door on a side surface of the material feeding barrel, wherein the seal door can be open or closed, disposing steel balls as cooling and crushing medium and disposing a spray cooling system in the working barrel; step b, using a hydraulic bearing device to support the material feeding barrel, opening the seal door, moving a material feeding hopper to a position directly above the material feeding port, moving a slag ladle to a position directly above the material feeding hopper by traction of a traveling crane, turning over the slag ladle to pour high-viscosity slag or ladle-bottom slag in the ladle into the material feeding barrel at one time, closing the seal door and then removing the material feeding hopper and the hydraulic bearing device; and step c, rotating the working barrel and the material feeding barrel simultaneously, so that under the combined action of the gravity component force in the axial direction of the material feeding barrel and the rotating force of the material feeding barrel, the high-temperature solid steel slag within the material feeding barrel moves downwards gradually as the material feeding barrel rotates, in the form of spiral feeding, and enters into the working barrel orderly, the high-temperature solid steel slag gradually transferred from the material feeding barrel is processed in the working barrel by continuously cooling and crushing blocky high-temperature solid steel slag by the cooling and crushing medium within the working barrel, using cooling water ejected from the spray cooling system to controllably cool and immerge to the crushed steel slag so as to rapidly stabilize the steel slag and make the steel slag have a normal temperature, and to achieve a heat-exchange cooling to the steel balls, and discharging the processed solid steel slag.